staging: lustre: prevent underflows in lnet_parse_reply()

I don't know if "hdr->payload_length;" can really be negative, but if so
then we shouldn't allow it.  Do the comparison as an unsigned.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/lnet/lib-move.c

@@ -1530,7 +1530,7 @@ lnet_parse_reply(lnet_ni_t *ni, lnet_msg_t *msg)
 	LASSERT(md->md_offset == 0);
 
 	rlength = hdr->payload_length;
-	mlength = min_t(int, rlength, md->md_length);
+	mlength = min_t(uint, rlength, md->md_length);
 
 	if (mlength < rlength &&
 	    (md->md_options & LNET_MD_TRUNCATE) == 0) {