SUNRPC: Fix typo in xdr_buf_subsegment's kdoc comment

Fix a typo.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xdr.c

@@ -1597,7 +1597,7 @@ EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
  *
  * @buf and @subbuf may be pointers to the same struct xdr_buf.
  *
- * Returns -1 if base of length are out of bounds.
+ * Returns -1 if base or length are out of bounds.
  */
 int xdr_buf_subsegment(const struct xdr_buf *buf, struct xdr_buf *subbuf,
 		       unsigned int base, unsigned int len)