drm/amdgpu/vcn2.0: add cancel_delayed_work_sync before power gate

Add cancel_delayed_work_sync before set power gating state
to avoid race condition issue when power gating.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c

@@ -262,6 +262,8 @@ static int vcn_v2_0_hw_fini(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
+	cancel_delayed_work_sync(&adev->vcn.idle_work);
+
 	if ((adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG) ||
 	    (adev->vcn.cur_state != AMD_PG_STATE_GATE &&
 	      RREG32_SOC15(VCN, 0, mmUVD_STATUS)))