IB/core: Remove smac and vlan id from qp_attr and ah_attr

Smac and vlan id could be resolved from the GID attribute, and thus
these attributes aren't needed anymore. Removing them.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Reviewed-By: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>