IPoIB: don't zero members after we allocate with kzalloc

ipoib_mcast_alloc() uses kzalloc(), so there's no need to zero out
members of the mcast struct after it's allocated.

Signed-off-by: Roland Dreier <[e-mail]>

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

···
 	mcast->dev = dev;
 	mcast->created = jiffies;
 	mcast->backoff = 1;
-	mcast->logcount = 0;
 
 	INIT_LIST_HEAD(&mcast->list);
 	INIT_LIST_HEAD(&mcast->neigh_list);
 	skb_queue_head_init(&mcast->pkt_queue);
-
-	mcast->ah    = NULL;
-	mcast->query = NULL;
 
 	return mcast;
 }