rdma/cxgb4: Simplify a structure initialization

This patch avoids that sparse reports the following warning:

drivers/infiniband/hw/cxgb4/qp.c:2269:34: warning: Using plain integer as NULL pointer

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Acked-by: Raju Rangoju <rajur@chelsio.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/cxgb4/qp.c

@@ -2266,7 +2266,7 @@ struct ib_qp *c4iw_get_qp(struct ib_device *dev, int qpn)
 
 void c4iw_dispatch_srq_limit_reached_event(struct c4iw_srq *srq)
 {
-	struct ib_event event = {0};
+	struct ib_event event = {};
 
 	event.device = &srq->rhp->ibdev;
 	event.element.srq = &srq->ibsrq;