IB/SA: Add OPA addr header

When importing the patch 57520751 (IB/SA: Add OPA path record type),
a new header file should have been added to the repo as part of the
patch.  However, as the patch didn't apply cleanly using git am, I
instead used patch manually, and followed that up with git add -u, which
misses new files.  This adds the new file back in.

Fixes: 57520751 (IB/SA: Add OPA path record type)
Signed-off-by: Doug Ledford <dledford@redhat.com>