IB/rdmavt: Add query and modify port stubs

This patch adds the query and modify port stubs. The query will mostly
entail the driver returning everything in the ib_port_attr which will get
handed back to the verbs layer. The modify will need some API helpers in
the driver. The send_trap and post_mad_send are still issues to address.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>