Remove bashism

Get rid of bash-ish "==" equivalence test in checking if the LUKS_KEY ends in
.gpg.  Use strict Bourne-compliant '=' instead.

defaults/initrd.scripts

@@ -827,7 +827,7 @@ openLUKS() {
 					fi
 					# At this point a candidate key exists (either mounted before or not)
 					good_msg "${LUKS_KEY} on device ${LUKS_KEYDEV} found" ${CRYPT_SILENT}
-					if [ $(echo ${LUKS_KEY} | grep -o '.gpg$') == ".gpg" ] && [ -e /sbin/gpg ] ; then
+					if [ $(echo ${LUKS_KEY} | grep -o '.gpg$') = ".gpg" ] && [ -e /sbin/gpg ] ; then
 						[ -e /dev/tty ] && mv /dev/tty /dev/tty.org
 						mknod /dev/tty c 5 1
 						cryptsetup_options="-d -"