package/base-files: add get_magic_long() to common upgrade script

Patch-by: Mark Mentovai <mark@moxienet.com>

SVN-Revision: 25117

package/base-files/files/lib/upgrade/common.sh

@@ -130,6 +130,10 @@ get_magic_word() {
 	get_image "$@" | dd bs=2 count=1 2>/dev/null | hexdump -v -n 2 -e '1/1 "%02x"'
 }
 
+get_magic_long() {
+	get_image "$@" | dd bs=4 count=1 2>/dev/null | hexdump -v -n 4 -e '1/1 "%02x"'
+}
+
 refresh_mtd_partitions() {
 	mtd refresh rootfs
 }