drm/radeon: switch UVD code to use UVD_NO_OP for padding

Replace packet2's with packet0 writes to UVD_NO_OP.  The
value written to UVD_NO_OP does not matter.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/cikd.h b/drivers/gpu/drm/radeon/cikd.h
index cead228..48db935 100644
--- a/drivers/gpu/drm/radeon/cikd.h
+++ b/drivers/gpu/drm/radeon/cikd.h
@@ -2069,6 +2069,7 @@
 #define UVD_UDEC_ADDR_CONFIG		0xef4c
 #define UVD_UDEC_DB_ADDR_CONFIG		0xef50
 #define UVD_UDEC_DBW_ADDR_CONFIG	0xef54
+#define UVD_NO_OP			0xeffc
 
 #define UVD_LMI_EXT40_ADDR		0xf498
 #define UVD_GP_SCRATCH4			0xf4e0