IB/rxe: replace refcount_inc with skb_get

Follow the advice from Bart, the function refcount_inc is replaced
with skb_get in commit 99dae690 ("IB/rxe: optimize mcast recv process")
and commit 86af6176 ("IB/rxe: remove unnecessary skb_clone").

CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Suggested-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_recv.c

@@ -311,7 +311,7 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
 		 * increase the users of the skb then post to the next qp
 		 */
 		if (mce->qp_list.next != &mcg->qp_list)
-			refcount_inc(&skb->users);
+			skb_get(skb);
 
 		pkt->qp = qp;
 		rxe_add_ref(qp);

drivers/infiniband/sw/rxe/rxe_resp.c

@@ -990,7 +990,7 @@ static int send_atomic_ack(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
 	memset((unsigned char *)SKB_TO_PKT(skb) + sizeof(ack_pkt), 0,
 	       sizeof(skb->cb) - sizeof(ack_pkt));
 
-	refcount_inc(&skb->users);
+	skb_get(skb);
 	res->type = RXE_ATOMIC_MASK;
 	res->atomic.skb = skb;
 	res->first_psn = ack_pkt.psn;