drm/amd/display: Extend dmub_cmd_psr_copy_settings_data struct

Reserve padding bytes for new feature implementation
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Ian Chen <ian.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h

@@ -1409,6 +1409,10 @@ struct dmub_cmd_psr_copy_settings_data {
 	 * Currently the support is only for 0 or 1
 	 */
 	uint8_t panel_inst;
+	/**
+	 * Explicit padding to 4 byte boundary.
+	 */
+	uint8_t pad3[4];
 };
 
 /**