IB/hfi1: OPFN interface

OPFN allows a pair of connected RC QPs to exchange a set of parameters
in succession. The parameter exchange itself is done using the IB compare
and swap request with a special virtual address. The request is triggered
using a reserved IB work request opcode. This patch implements the OPFN
interface to initialize, start, process, and reset the OPFN request.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>