IB/i40iw: Use kmemdup rather than open coding

Use kmemdump instead of kzmalloc + memcpy.
Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/i40iw/i40iw_cm.c

@@ -4276,11 +4276,11 @@ static void i40iw_qhash_ctrl(struct i40iw_device *iwdev,
 	/* if not found then add a child listener if interface is going up */
 	if (!ifup)
 		return;
-	child_listen_node = kzalloc(sizeof(*child_listen_node), GFP_ATOMIC);
+	child_listen_node = kmemdup(parent_listen_node,
+			sizeof(*child_listen_node), GFP_ATOMIC);
 	if (!child_listen_node)
 		return;
 	node_allocated = true;
-	memcpy(child_listen_node, parent_listen_node, sizeof(*child_listen_node));
 
 	memcpy(child_listen_node->loc_addr, ipaddr,  ipv4 ? 4 : 16);