rds:Remove unnecessary ib_ring unalloc

In the function rds_ib_xmit_atomic, ib_ring is not allocated
successfully. As such, it is not necessary to unalloc it.

Cc: Joe Jin <joe.jin@oracle.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rds/ib_send.c

@@ -770,7 +770,6 @@ int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
 
 	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
 	if (work_alloc != 1) {
-		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 		rds_ib_stats_inc(s_ib_tx_ring_full);
 		ret = -ENOMEM;
 		goto out;