IB/hfi1: OPFN support discovery

OPFN (Omni Path Feature Negotiation) support discovery allows a RC QP to
announce that it supports OPFN and also discover if OPFN is supported by
the peer QP. OPFN parameter negotiation is skipped unless OPFN support is
first discovered. OPFN support is announced by claiming what was
the reserved bit in dword 1 of OmniPath modified base transport header
in requests and responses.

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>