drm/amd/amdgpu: enable PG_EN bit in powergating UVD

Enable the PG_EN bit just before the SMU would be tasked
with the PG transition.
Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/uvd_v6_0.c

@@ -997,6 +997,8 @@ static int uvd_v6_0_set_powergating_state(void *handle,
 	if (!(adev->pg_flags & AMD_PG_SUPPORT_UVD))
 		return 0;
 
+	WREG32(mmUVD_POWER_STATUS, UVD_POWER_STATUS__UVD_PG_EN_MASK);
+
 	if (state == AMD_PG_STATE_GATE) {
 		uvd_v6_0_stop(adev);
 		return 0;