cmd_zfs: normalize 'file not found' errors

Signed-off-by: Luka Perkov <luka@openwrt.org>
diff --git a/common/cmd_zfs.c b/common/cmd_zfs.c
index 9110868..0aed29e 100644
--- a/common/cmd_zfs.c
+++ b/common/cmd_zfs.c
@@ -95,7 +95,7 @@
 	memset(&zfile, 0, sizeof(zfile));
 	zfile.device = &vdev;
 	if (zfs_open(&zfile, filename)) {
-		printf("** File not found %s\n", filename);
+		printf("** File not found %s **\n", filename);
 		return 1;
 	}