EDAC: Don't try to cancel workqueue when it's never setup

EDAC: Don't try to cancel workqueue when it's never setup

We only setup a workqueue for edac devices that use the polling
method. We still try to cancel the workqueue if an edac_device
uses the irq method though. This causes a warning from debug
objects when we remove an edac device:

WARNING: CPU: 0 PID: 56 at lib/debugobjects.c:260 debug_print_object+0x98/0xc0()
ODEBUG: assert_init not available (active state 0) object type: timer_list hint: stub_timer+0x0/0x28
Modules linked in: krait_edac(-)
CPU: 0 PID: 56 Comm: rmmod Not tainted 3.12.0-rc2-00035-g15292a0 #69
(unwind_backtrace+0x0/0x144)
(show_stack+0x20/0x24)
(dump_stack+0x74/0xb4)
(warn_slowpath_common+0x78/0x9c)
(warn_slowpath_fmt+0x40/0x48)
(debug_print_object+0x98/0xc0)
(debug_object_assert_init+0xdc/0xec)
(del_timer+0x24/0x7c)
(try_to_grab_pending+0xc0/0x1b0)
(cancel_delayed_work+0x2c/0xa0)
(edac_device_workq_teardown+0x1c/0x38)
(edac_device_del_device+0xb8/0xe4)
(krait_edac_remove+0x50/0x70 [krait_edac])
(platform_drv_remove+0x24/0x28)
(__device_release_driver+0x68/0xc0)
(driver_detach+0xc4/0xc8)
(bus_remove_driver+0xac/0x114)
(driver_unregister+0x38/0x58)
(platform_driver_unregister+0x1c/0x20)
(krait_edac_driver_exit+0x14/0x1c [krait_edac])
(SyS_delete_module+0x178/0x2b4)

Fix it by skipping the workqueue teardown for such devices.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/1388434457-4194-2-git-send-email-sboyd@codeaurora.org
Signed-off-by: Borislav Petkov <bp@suse.de>