IB/rdmavt: Add pkey support

Add pkey table in rdi per port data structure. Also bring in related pkey
functions. Drivers will still be responsible for allocating and
maintaining the pkey table. However they need to tell rdmavt where to find
the pkey table. We can not move the pkey table up into rdmavt because
drivers need to manipulate this long before registering with it.

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