io: fix sign of errno value passed to error report

When reporting the number of FDs has been exceeded, pass
EINVAL to error_setg_errno, rather than -EINVAL.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

io/channel-socket.c

@@ -502,7 +502,7 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
 
     if (nfds) {
         if (nfds > SOCKET_MAX_FDS) {
-            error_setg_errno(errp, -EINVAL,
+            error_setg_errno(errp, EINVAL,
                              "Only %d FDs can be sent, got %zu",
                              SOCKET_MAX_FDS, nfds);
             return -1;