drm/amdgpu: Drop redundant queue NULL check in hang detect worker

drm/amdgpu: Drop redundant queue NULL check in hang detect worker

amdgpu_userq_hang_detect_work() retrieves the queue pointer using
container_of() from the embedded work item.

Since the work structure is part of struct amdgpu_usermode_queue,
the returned queue pointer cannot be NULL in normal execution.

Remove the redundant !queue check and keep the validation for
queue->userq_mgr.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c:159 amdgpu_userq_hang_detect_work() warn: can 'queue' even be NULL?

Fixes: 290f46cf5726 ("drm/amdgpu: Implement user queue reset functionality")
Cc: Jesse Zhang <Jesse.Zhang@amd.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Acked-by: Jesse Zhang <jesse.zhang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>