IB/core: Add gid_type to gid attribute

In order to support multiple GID types, we need to store the gid_type
with each GID. This is also aligned with the RoCE v2 annex "RoCEv2 PORT
GID table entries shall have a "GID type" attribute that denotes the L3
Address type". The currently supported GID is IB_GID_TYPE_IB which is
also RoCE v1 GID type.

This implies that gid_type should be added to roce_gid_table meta-data.

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