Fix the test to use the variable

Signed-off-by: Manuel Amador (Rudd-O) <rudd-o@rudd-o.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4645

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

@@ -56,7 +56,7 @@ esac
 if [ ${wait_for_zfs} -eq 1 ]; then
 	ln -s /dev/null /dev/root 2>/dev/null
 	initqueuedir="${hookdir}/initqueue/finished"
-	test -d initqueuedir || {
+	test -d "${initqueuedir}" || {
 		initqueuedir="${hookdir}/initqueue-finished"
 	}
 	echo '[ -e /dev/zfs ]' > "${initqueuedir}/zfs.sh"