drm/amdgpu/userq: unlock cancel_delayed_work_sync for hang_detect_work

drm/amdgpu/userq: unlock cancel_delayed_work_sync for hang_detect_work

cancel_delayed_work_sync for work hand_detect_work should not be
locked since the amdgpu_userq_hang_detect_work also need the same
mutex and when they run together it could be a deadlock.

we do not need to hold the mutex for
cancel_delayed_work_sync(&queue->hang_detect_work). With this in place
if cancel and worker thread run at same time they will not deadlock.

Due to any failures if there is a hand detect and reset that there a
deadlock scenarios between cancel and running the main thread.

[ 243.118276] task:kworker/9:0 state:D stack:0 pid:73 tgid:73 ppid:2 task_flags:0x4208060 flags:0x00080000
[ 243.118283] Workqueue: events amdgpu_userq_hang_detect_work [amdgpu]
[ 243.118636] Call Trace:
[ 243.118639] <TASK>
[ 243.118644] __schedule+0x581/0x1810
[ 243.118649] ? srso_return_thunk+0x5/0x5f
[ 243.118656] ? srso_return_thunk+0x5/0x5f
[ 243.118659] ? wake_up_process+0x15/0x20
[ 243.118665] schedule+0x64/0xe0
[ 243.118668] schedule_preempt_disabled+0x15/0x30
[ 243.118671] __mutex_lock+0x346/0x950
[ 243.118677] __mutex_lock_slowpath+0x13/0x20
[ 243.118681] mutex_lock+0x2c/0x40
[ 243.118684] amdgpu_userq_hang_detect_work+0x63/0x90 [amdgpu]
[ 243.118888] process_scheduled_works+0x1f0/0x450
[ 243.118894] worker_thread+0x27f/0x370
[ 243.118899] kthread+0x1ed/0x210
[ 243.118903] ? __pfx_worker_thread+0x10/0x10
[ 243.118906] ? srso_return_thunk+0x5/0x5f
[ 243.118909] ? __pfx_kthread+0x10/0x10
[ 243.118913] ret_from_fork+0x10f/0x1b0
[ 243.118916] ? __pfx_kthread+0x10/0x10
[ 243.118920] ret_from_fork_asm+0x1a/0x30

Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>