RDMA/siw: Use iov.iov_len in kernel_sendmsg

We can pass iov.iov_len here.
Acked-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20231113115726.12762-4-guoqing.jiang@linux.devSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/sw/siw/siw_qp_tx.c

@@ -292,8 +292,7 @@ static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
 				    (char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent,
 			    .iov_len = c_tx->ctrl_len - c_tx->ctrl_sent };
 
-	int rv = kernel_sendmsg(s, &msg, &iov, 1,
-				c_tx->ctrl_len - c_tx->ctrl_sent);
+	int rv = kernel_sendmsg(s, &msg, &iov, 1, iov.iov_len);
 
 	if (rv >= 0) {
 		c_tx->ctrl_sent += rv;