drm/i915/guc: Don't forget to free GuC error log

drm/i915/guc: Don't forget to free GuC error log

We're freeing GuC error log in uc_fini_hw() that matches
corresponding uc_init_hw() but we missed the point that this
log object is copied on error path and in case of failure in
uc_init_hw() we will leak this object as uc_fini_hw() is
never called.

If we free this log object as part of the late uC cleanup, where
we also release other firmware objects, we can avoid this BUG:

[70841.001413] BUG drm_i915_gem_object (Tainted: G     U  W       ): Objects remaining in drm_i915_gem_object on __kmem_cache_shutdown()
[70841.001436] INFO: Slab 0x00000000c94e41af objects=21 used=1 fp=0x000000001d60c40a flags=0x8000000000008100

[70841.001466] Call Trace:
[70841.001471]  dump_stack+0x5e/0x8e
[70841.001476]  slab_err+0x99/0xb0
[70841.001483]  ? __slab_alloc.isra.24.constprop.29+0x62/0x70
[70841.001491]  ? __kmalloc+0x1f5/0x320
[70841.001497]  __kmem_cache_shutdown+0x18b/0x400
[70841.001505]  shutdown_cache+0x13/0x1c0
[70841.001511]  kmem_cache_destroy+0x1c2/0x240
[70841.001517]  ? __mutex_unlock_slowpath+0x38/0x270
[70841.001559]  i915_gem_load_cleanup+0xbc/0x130 [i915]
[70841.001595]  i915_driver_cleanup_early+0x11/0x60 [i915]
[70841.001630]  i915_driver_load+0x708/0x1720 [i915]
[70841.001638]  ? trace_hardirqs_on_caller+0xe2/0x1c0
[70841.001673]  i915_pci_probe+0x2d/0x90 [i915]
[70841.001680]  pci_device_probe+0x9c/0x120
[70841.001687]  driver_probe_device+0x2a9/0x490
[70841.001694]  __driver_attach+0xd9/0xe0
[70841.001700]  ? driver_probe_device+0x490/0x490
[70841.001705]  bus_for_each_dev+0x57/0x90
[70841.001712]  bus_add_driver+0x1eb/0x260
[70841.001717]  ? 0xffffffffa0685000
[70841.001723]  driver_register+0x52/0xc0
[70841.001728]  ? 0xffffffffa0685000
[70841.001733]  do_one_initcall+0x39/0x170
[70841.001739]  ? rcu_read_lock_sched_held+0x6f/0x80
[70841.001746]  ? kmem_cache_alloc_trace+0x27b/0x2e0
[70841.001753]  do_init_module+0x56/0x1ec
[70841.001759]  load_module+0x219e/0x2550
[70841.001766]  ? vfs_read+0x121/0x140
[70841.001774]  ? SyS_finit_module+0xa5/0xe0
[70841.001779]  SyS_finit_module+0xa5/0xe0
[70841.001788]  entry_SYSCALL_64_fastpath+0x22/0x8f

[70841.001806] INFO: Object 0x00000000eab7ed96 @offset=6208
[70841.001850] INFO: Allocated in i915_gem_object_create.part.32+0x1f/0x260 [i915] age=38 cpu=0 pid=2708
[70841.001861] 	kmem_cache_alloc+0x23d/0x2d0
[70841.001897] 	i915_gem_object_create.part.32+0x1f/0x260 [i915]
[70841.001937] 	intel_guc_allocate_vma+0x15/0x100 [i915]
[70841.001977] 	intel_guc_log_create+0x34/0x1c0 [i915]
[70841.002014] 	intel_guc_init+0x5a/0x100 [i915]
[70841.002051] 	intel_uc_init+0x3e/0xb0 [i915]
[70841.002089] 	i915_gem_init+0x18e/0x540 [i915]
[70841.002123] 	i915_driver_load+0xa7a/0x1720 [i915]
[70841.002159] 	i915_pci_probe+0x2d/0x90 [i915]
[70841.002165] 	pci_device_probe+0x9c/0x120
[70841.002171] 	driver_probe_device+0x2a9/0x490
[70841.002177] 	__driver_attach+0xd9/0xe0
[70841.002182] 	bus_for_each_dev+0x57/0x90
[70841.002188] 	bus_add_driver+0x1eb/0x260
[70841.002193] 	driver_register+0x52/0xc0
[70841.002198] 	do_one_initcall+0x39/0x170
[70841.002462] kmem_cache_destroy drm_i915_gem_object: Slab cache still has objects

[70841.002491] Call Trace:
[70841.002497]  dump_stack+0x5e/0x8e
[70841.002503]  kmem_cache_destroy+0x1e0/0x240
[70841.002509]  ? __mutex_unlock_slowpath+0x38/0x270
[70841.002551]  i915_gem_load_cleanup+0xbc/0x130 [i915]
[70841.002586]  i915_driver_cleanup_early+0x11/0x60 [i915]
[70841.002621]  i915_driver_load+0x708/0x1720 [i915]
[70841.002629]  ? trace_hardirqs_on_caller+0xe2/0x1c0
[70841.002664]  i915_pci_probe+0x2d/0x90 [i915]
[70841.002671]  pci_device_probe+0x9c/0x120
[70841.002678]  driver_probe_device+0x2a9/0x490
[70841.002684]  __driver_attach+0xd9/0xe0
[70841.002690]  ? driver_probe_device+0x490/0x490
[70841.002696]  bus_for_each_dev+0x57/0x90
[70841.002702]  bus_add_driver+0x1eb/0x260
[70841.002708]  ? 0xffffffffa0685000
[70841.002713]  driver_register+0x52/0xc0
[70841.002719]  ? 0xffffffffa0685000
[70841.002724]  do_one_initcall+0x39/0x170
[70841.002731]  ? rcu_read_lock_sched_held+0x6f/0x80
[70841.002737]  ? kmem_cache_alloc_trace+0x27b/0x2e0
[70841.002745]  do_init_module+0x56/0x1ec
[70841.002751]  load_module+0x219e/0x2550
[70841.002758]  ? vfs_read+0x121/0x140
[70841.002766]  ? SyS_finit_module+0xa5/0xe0
[70841.002772]  SyS_finit_module+0xa5/0xe0
[70841.002781]  entry_SYSCALL_64_fastpath+0x22/0x8f

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180131173241.19704-2-michal.wajdeczko@intel.com
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>