SUNRPC: fix ternary sign expansion bug in tracing

This code is supposed to pass negative "err" values for tracing but it
passes positive values instead.  The problem is that the
trace_svcsock_tcp_send() function takes a long but "err" is an int and
"sent" is a u32.  The negative is first type promoted to u32 so it
becomes a high positive then it is promoted to long and it stays
positive.

Fix this by casting "err" directly to long.

Fixes: 998024de ("SUNRPC: Add more svcsock tracepoints")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/svcsock.c

@@ -1174,7 +1174,7 @@ static int svc_tcp_sendto(struct svc_rqst *rqstp)
 	tcp_sock_set_cork(svsk->sk_sk, true);
 	err = svc_tcp_sendmsg(svsk->sk_sock, xdr, marker, &sent);
 	xdr_free_bvec(xdr);
-	trace_svcsock_tcp_send(xprt, err < 0 ? err : sent);
+	trace_svcsock_tcp_send(xprt, err < 0 ? (long)err : sent);
 	if (err < 0 || sent != (xdr->len + sizeof(marker)))
 		goto out_close;
 	if (atomic_dec_and_test(&svsk->sk_sendqlen))