RDMA/netdev: Fix netlink support in IPoIB

IPoIB netlink support was broken by the below commit since integrating
the rdma_netdev support relies on an allocation flow for netdevs that
was controlled by the ipoib driver while netdev's rtnl_newlink
implementation assumes that the netdev will be allocated by netlink.
Such situation leads to crash in __ipoib_device_add, once trying to
reuse netlink device.

This patch fixes the kernel oops for both mlx4 and mlx5
devices triggered by the following command:

Fixes: cd565b4b51e5 ("IB/IPoIB: Support acceleration options callbacks")
Signed-off-by: Denis Drozdov <denisd@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 020216c..0ed5d91 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -4198,4 +4198,11 @@ struct net_device *rdma_alloc_netdev(struct ib_device *device, u8 port_num,
 				     enum rdma_netdev_t type, const char *name,
 				     unsigned char name_assign_type,
 				     void (*setup)(struct net_device *));
+
+int rdma_init_netdev(struct ib_device *device, u8 port_num,
+		     enum rdma_netdev_t type, const char *name,
+		     unsigned char name_assign_type,
+		     void (*setup)(struct net_device *),
+		     struct net_device *netdev);
+
 #endif /* IB_VERBS_H */