staging/hfi1: Add TID free/clear function bodies

Up to now, the functions which cleared the programmed
TID entries and gave PSM the list of invalidated TID entries
were just stubs. With this commit, the bodies of these
functions are added.

This commit is a bit asymmetric as it only contains the
free code path. This is done on purpose to help with patch
reviews as the programming code path is much longer.

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>