RDMA/core: Set gid_attr.ndev for iWARP devices

Have the iwarp side properly set the ndev in the device's sgid_attrs
so that address resolution can treat it more like a RoCE device.

Link: https://lore.kernel.org/r/168960673933.3007.8043081822081877578.stgit@manet.1015granger.netSuggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/cache.c

@@ -1457,6 +1457,17 @@ static int config_non_roce_gid_cache(struct ib_device *device,
 				 i);
 			goto err;
 		}
+
+		if (rdma_protocol_iwarp(device, port)) {
+			struct net_device *ndev;
+
+			ndev = ib_device_get_netdev(device, port);
+			if (!ndev)
+				continue;
+			RCU_INIT_POINTER(gid_attr.ndev, ndev);
+			dev_put(ndev);
+		}
+
 		gid_attr.index = i;
 		tprops->subnet_prefix =
 			be64_to_cpu(gid_attr.gid.global.subnet_prefix);