qcacmn: check if peer pointer is NULL

In dp_rx_process function, check if peer pointer is NULL
before using as argument when calling dp_rx_deliver_to_stack.

Change-Id: I6584c79047a809f28e65faad47d1c7220e7057bb
CRs-Fixed: 2470345

dp/wifi3.0/dp_rx.c

@@ -2038,7 +2038,7 @@ done:
 		dp_peer_unref_del_find_by_id(peer);
 	}
 
-	if (deliver_list_head)
+	if (deliver_list_head && peer)
 		dp_rx_deliver_to_stack(vdev, peer, deliver_list_head,
 				       deliver_list_tail);