IB/core: Add ROCE_UDP_ENCAP (RoCE V2) type

Adding RoCE v2 GID type and port type. Vendors
which support this type will get their GID table
populated with RoCE v2 GIDs automatically.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>