cleanup: don't chattr if it's not immutable.

On kernels without the fix for Samsung laptops, the cleanup script will
fail because the efi variables in sysfs files aren't immutable.  Don't
try to unset the immutable flag if it's not set.

This is discussed here: #69 (comment)

Signed-off-by: Peter Jones <pjones@redhat.com>

linux/cleanup.in

@@ -21,7 +21,9 @@ for x in @@ESPMOUNTPOINT@@/EFI/@@EFIDIR@@/fw/fwupdate-* ; do
 done
 for x in /sys/firmware/efi/efivars/fwupdate-*-0abba7dc-e516-4167-bbf5-4d9d1c739416 ; do
 	if [ "${x}" != "/sys/firmware/efi/efivars/fwupdate-*-0abba7dc-e516-4167-bbf5-4d9d1c739416" ]; then
-		chattr -i "${x}"
+		if lsattr "${x}" 2>/dev/null | cut -d\  -f1 | cut -d- -f5 | grep -q i ; then
+			chattr -i "${x}"
+		fi
 		rm -f "${x}"
 	fi
 done