scripts: fix wrong usage of '==' operator

[base-files] shell-scripting: fix wrong usage of '==' operator

normally the '==' is used for invoking a regex parser and is a bashism.
all of the fixes just want to compare a string. the used busybox-ash
will silently "ignore" this mistake, but make it portable/clean at least.

this patch does not change the behavior/logic of the scripts.

Signed-off-by: Bastian Bittorf <bittorf@bluebottle.com>

SVN-Revision: 42911

target/linux/ramips/base-files/lib/preinit/04_handle_checksumming

@@ -44,7 +44,7 @@ do_checksumming_disable() {
 		local rootfs_data_len=$(grep \"rootfs_data\" /proc/mtd | awk -F' ' '{print "0x"$2}')
 		local offset=$(echo "$rootfs_len $rootfs_data_len 0x40" | awk -F' ' '{printf "%i",$1-$2-$3}')
 		local signature=$(dd if=$rootfs_mtd skip=$offset bs=1 count=4 2>/dev/null | hexdump -v -n 4 -e '1/1 "%02x"')
-		if [ "$signature" == "27051956" ]; then
+		if [ "$signature" = "27051956" ]; then
 			dd conv=notrunc if=$rootfs_mtd skip=$offset of=$firmware_mtd bs=1 count=64 2>/dev/null
 		fi
 	;;