NFS: Off-by-one length error in string handling

The hostname was getting truncated in the new text-based NFS mount API.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -1153,7 +1153,7 @@ static int nfs_validate_mount_data(struct nfs_mount_data **options,
 		c = strchr(dev_name, ':');
 		if (c == NULL)
 			return -EINVAL;
-		len = c - dev_name - 1;
+		len = c - dev_name;
 		if (len > sizeof(data->hostname))
 			return -EINVAL;
 		strncpy(data->hostname, dev_name, len);