drm/amdgpu/vcn: fix race condition issue for vcn start
Fix race condition issue when multiple vcn starts are called.
v2: Removed checking the return value of cancel_delayed_work_sync()
to prevent possible races here.
v3: Add total_submission_cnt to avoid gate power unexpectedly.
v4: Remove extra counter check, and reduce counter before idle
work schedule
Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>