IB/rdmavt: Add AH to rdmavt

Original patch is from Kamal Heib <kamalh@mellanox.com>. It has
been split into three separate patches. This one for rdmavt,
a follow on for qib, and one for hfi1.

Create datastructure for address handle and implement the
create/destroy/modify/query of address handle for rdmavt.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Kamal Heib <kamalh@mellanox.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>