[CMD][SECO_CONFIG] Fix warning: assignment discards const qualifier

cmd/seco_config_lib.c

@@ -928,7 +928,7 @@ int set_video_mode( int fdt_selected_device ) {
 #endif  /* CONFIG_OF_LIBFDT_OVERLAY */
 	int fw_num;
 	fw_t *firmware;
-	char *get_fw_video_list;
+	const char *get_fw_video_list;
 	char fw_video_list[256];
 
 	/* select video mode configuration */
@@ -1296,7 +1296,7 @@ int set_touch_mode( int fdt_selected_device ) {
 	// char *peripheral_list_overlay;
 	int fw_num;
 	fw_t *firmware;
-	char *get_fw_video_list;
+	const char *get_fw_video_list;
 	char fw_video_list[256];
 
 	peripheral_overlay_selections = malloc( sizeof(int) *  gd->boot_setup.overlay_peripheral_num );