staging/hfi1: Add definitions needed for TID cache

In preparation for adding the TID caching support, there is a set
of headers, structures, and variables which will be needed. This
commit adds them to the hfi.h header file.

Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>