add switch to not save configuration over the reflash in noninteractive mode

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@12714 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/base-files/files/sbin/sysupgrade

@@ -16,6 +16,7 @@ while [ -n "$1" ]; do
 		-d) export DELAY="$2"; shift;;
 		-v) export VERBOSE="$(($VERBOSE + 1))";;
 		-q) export VERBOSE="$(($VERBOSE - 1))";;
+		-n) export SAVE_CONFIG=0
 		-*)
 			echo "Invalid option: $1"
 			exit 1
@@ -38,6 +39,7 @@ Usage: $0 [options] <image file or URL>
 Options:
 	-d <delay>   add a delay before rebooting
 	-i           interactive mode
+	-n	     do not save configuration over reflash
 	-q           less verbose
 	-v           more verbose