drm/i915: Silence warning for no vlv powercontext

drm/i915: Silence warning for no vlv powercontext

Along a module load error path, we may try to cleanup the powercontext
even before we have allocated it.  Reorganising GT powermanagement is an
 on going process, so for simplicity handle it.

[  522.733832] WARN_ON(!dev_priv->vlv_pctx)
[  522.733986] WARNING: CPU: 1 PID: 3856 at drivers/gpu/drm/i915/intel_pm.c:7350 intel_cleanup_gt_powersave+0x5f/0x70 [i915]
[  522.733991] Modules linked in: i915(+) vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic btusb btrtl btbcm btintel intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul bluetooth snd_hda_codec ghash_clmulni_intel snd_hwdep snd_hda_core ecdh_generic lpc_ich r8169 snd_pcm mii i2c_hid prime_numbers [last unloaded: i915]
[  522.734105] CPU: 1 PID: 3856 Comm: drv_module_relo Tainted: G     U            4.18.0-rc4-CI-CI_DRM_4474+ #1
[  522.734110] Hardware name: \xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff \xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff/DN2820FYK, BIOS FYBYT10H.86A.0059.2017.0607.2130 06/07/2017
[  522.734193] RIP: 0010:intel_cleanup_gt_powersave+0x5f/0x70 [i915]
[  522.734197] Code: 00 74 0d 48 c7 83 68 a6 00 00 00 00 00 00 eb c8 e8 36 6f 37 e1 eb ec 48 c7 c6 c5 7a 3d a0 48 c7 c7 b5 78 3d a0 e8 71 04 e0 e0 <0f> 0b eb aa 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f3 c3 0f 1f 40
[  522.734445] RSP: 0018:ffffc900004f3af0 EFLAGS: 00010282
[  522.734453] RAX: 0000000000000000 RBX: ffff880106360000 RCX: 0000000000000001
[  522.734458] RDX: 0000000080000001 RSI: ffffffff820c65c4 RDI: 00000000ffffffff
[  522.734463] RBP: ffff880106360000 R08: 000000009f79baee R09: 0000000000000000
[  522.734467] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88013b3133f8
[  522.734472] R13: 00000000ffffffed R14: ffff880106360d58 R15: ffff88013b3133f8
[  522.734477] FS:  00007f43f70af980(0000) GS:ffff88013fd00000(0000) knlGS:0000000000000000
[  522.734481] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  522.734486] CR2: 000055a13a787580 CR3: 00000001325e6000 CR4: 00000000001006e0
[  522.734490] Call Trace:
[  522.734595]  intel_modeset_cleanup+0xcf/0x140 [i915]
[  522.734682]  i915_driver_load+0xc85/0x10a0 [i915]
[  522.734694]  ? _raw_spin_unlock_irqrestore+0x4c/0x60
[  522.734703]  ? trace_hardirqs_on_caller+0xe0/0x1b0
[  522.734790]  i915_pci_probe+0x29/0x90 [i915]
[  522.734801]  pci_device_probe+0xa1/0x130
[  522.734813]  driver_probe_device+0x306/0x480
[  522.734824]  __driver_attach+0xdb/0x100
[  522.734830]  ? driver_probe_device+0x480/0x480
[  522.734836]  ? driver_probe_device+0x480/0x480
[  522.734844]  bus_for_each_dev+0x74/0xc0
[  522.734855]  bus_add_driver+0x15f/0x250
[  522.734863]  ? 0xffffffffa0793000
[  522.734870]  driver_register+0x56/0xe0
[  522.734877]  ? 0xffffffffa0793000
[  522.734883]  do_one_initcall+0x58/0x370
[  522.734893]  ? do_init_module+0x1d/0x1ea
[  522.734900]  ? rcu_read_lock_sched_held+0x6f/0x80
[  522.734906]  ? kmem_cache_alloc_trace+0x282/0x2e0
[  522.734918]  do_init_module+0x56/0x1ea
[  522.734927]  load_module+0x2435/0x2b20
[  522.734965]  ? __se_sys_finit_module+0xd3/0xf0
[  522.734972]  __se_sys_finit_module+0xd3/0xf0
[  522.734995]  do_syscall_64+0x55/0x190
[  522.735003]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  522.735009] RIP: 0033:0x7f43f675d839
[  522.735014] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48
[  522.735260] RSP: 002b:00007ffe69384238 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[  522.735269] RAX: ffffffffffffffda RBX: 000056100e387090 RCX: 00007f43f675d839
[  522.735273] RDX: 0000000000000000 RSI: 000056100e37bff0 RDI: 0000000000000003
[  522.735278] RBP: 000056100e37bff0 R08: 0000000000000000 R09: 0000000000000000
[  522.735282] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
[  522.735286] R13: 000056100e37c890 R14: 0000000000000020 R15: 0000000000000027
[  522.735309] irq event stamp: 1389594
[  522.735316] hardirqs last  enabled at (1389593): [<ffffffff810f896c>] console_unlock+0x3fc/0x600
[  522.735323] hardirqs last disabled at (1389594): [<ffffffff81a0111c>] error_entry+0x7c/0x100
[  522.735329] softirqs last  enabled at (1389356): [<ffffffff81c0034f>] __do_softirq+0x34f/0x505
[  522.735336] softirqs last disabled at (1389335): [<ffffffff8108c7b9>] irq_exit+0xa9/0xc0
[  522.735432] WARNING: CPU: 1 PID: 3856 at drivers/gpu/drm/i915/intel_pm.c:7350 intel_cleanup_gt_powersave+0x5f/0x70 [i915]

Testcase: igt/drv_module_reload/basic-reload-inject
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712105454.16091-1-chris@chris-wilson.co.uk