IB/cma: IBoE (RoCE) IP-based GID addressing

Currently, the IB core and specifically the RDMA-CM assumes that IBoE
(RoCE) gids encode related Ethernet netdevice interface MAC address
and possibly VLAN id.

Change GIDs to be treated as they encode interface IP address.

Since Ethernet layer 2 address parameters are not longer encoded
within gids, we have to extend the Infiniband address structures (e.g.
ib_ah_attr) with layer 2 address parameters, namely mac and vlan.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>