tests: zfs_share_005: don't fail open

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13259

tests/zfs-tests/tests/functional/cli_root/zfs_share/zfs_share_005_pos.ksh

@@ -82,7 +82,7 @@ do
 		IFS=',' read -r _ option _ <<<"$option"
 	fi
 
-	log_must eval "showshares_nfs | grep -q $option"
+	log_must eval "showshares_nfs | grep -q \"$option\""
 
 	((i = i + 1))
 done