drm/amdgpu: enable DPG mode for Navi12

Enable Dynamic Power Gating VCN for Navi12.
Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Reviewed-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -615,7 +615,7 @@ static int nv_common_early_init(void *handle)
 		break;
 	case CHIP_NAVI12:
 		adev->cg_flags = 0;
-		adev->pg_flags = 0;
+		adev->pg_flags = AMD_PG_SUPPORT_VCN_DPG;
 		adev->external_rev_id = adev->rev_id + 0xa;
 		break;
 	default: