Use test(1) in a proper way

Use the correct operators to check the expected data type.

Signed-off-by: Soeren Tempel <soeren+git@soeren-tempel.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3093

dracut/90zfs/parse-zfs.sh.in

@@ -52,7 +52,7 @@ esac
 
 # Make sure Dracut is happy that we have a root and will wait for ZFS
 # modules to settle before mounting.
-if [ "${wait_for_zfs}" = "1" ]; then
+if [ ${wait_for_zfs} -eq 1 ]; then
 	ln -s /dev/null /dev/root 2>/dev/null
 	echo '[ -e /dev/zfs ]' > $hookdir/initqueue/finished/zfs.sh
 fi