IB/mlx4: Add support for setting RoCEv2 gids in hardware

To tell hardware about a gid with type RoCEv2, software needs a new
modifier to the SET_PORT command: MLX4_SET_PORT_ROCE_ADDR. This can
replace the old method, MLX4_SET_PORT_GID_TABLE, for  RoCEv1 gids.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>