staging/hfi1: TID group definitions and support funcs

Definitions and functions use to manage sets of TID/RcvArray groups.
These will be used by the TID cacheline functionality coming with
later patches.

TID groups (or RcvArray groups) are groups of TID/RcvArray entries
organized in sets of 8 and aligned on cacheline boundaries. The
TID/RcvArray entries are managed in this way to make taking
advantage of write-combining easier - each group is a entire
cacheline.

rcv_array_wc_fill() is provided to allow of generating writes to
TIDs which are not currently being used in order to cause the
flush of the write-combining buffer.

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>