IB/rdmavt: Add an ibport data structure to rdmavt

Converge the ibport data structures of qib and hfi1 into a common ib
port structure. Also provides a place to keep track of these ports
in case rdmavt needs it. Along with this goes an attach and detach
function for drivers to use to notify rdmavt of the ports.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>