IB/core: Work on the caller socket net namespace in nldev_newlink()

While creating new RDMA devices based on netdevice name, consider the net
namespace of the caller skb's socket similar to rest of the doit()
callbacks and nldev_dellink() which deletes the RDMA device created using
nldev_newlink().

Fixes: 3856ec4b ("RDMA/core: Add RDMA_NLDEV_CMD_NEWLINK/DELLINK support")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/nldev.c

@@ -1476,7 +1476,7 @@ static int nldev_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	nla_strlcpy(ndev_name, tb[RDMA_NLDEV_ATTR_NDEV_NAME],
 		    sizeof(ndev_name));
 
-	ndev = dev_get_by_name(&init_net, ndev_name);
+	ndev = dev_get_by_name(sock_net(skb->sk), ndev_name);
 	if (!ndev)
 		return -ENODEV;