Use MAC-based GID format for the GID table entries in mlx5ib(4) to be

Use MAC-based GID format for the GID table entries in mlx5ib(4) to be
compatible with the ibcore module in FreeBSD 10-stable.

This fixes RDMA over VLAN, because the MAC-based GID format embeds
the VLAN ID into the GID itself and this is what ibcore expects when
requesting GID indexes from the GID cache.

RoCE V1.5 and V2 is not supported in 10-stable by mlx5ib(4).
This is a direct commit.

Sponsored by:	Mellanox Technologies

git-svn-id: svn://svn.freebsd.org/base/stable/10@325599 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f