IB/hfi1: Rename TID mmu_rb_* functions

Clarify the names of the TID mmu functions.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>