IB/rxe: double free on error

"goto err;" has it's own kfree_skb() call so it's a double free.  We
only need to free on the "goto exit;" path.

Fixes: 8700e3e7 ("Soft RoCE driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_req.c

@@ -729,11 +729,11 @@ int rxe_requester(void *arg)
 	ret = rxe_xmit_packet(to_rdev(qp->ibqp.device), qp, &pkt, skb);
 	if (ret) {
 		qp->need_req_skb = 1;
-		kfree_skb(skb);
 
 		rollback_state(wqe, qp, &rollback_wqe, rollback_psn);
 
 		if (ret == -EAGAIN) {
+			kfree_skb(skb);
 			rxe_run_task(&qp->req.task, 1);
 			goto exit;
 		}