Remove hack to support old version tpr version 80

This break reading of master tpr version 80 (used up to Oct 16,
e56dd547) which added support for fbposres. There is no simple way
of supporting F_FBPOSRES in ftupd for 80 but not for 81-89. The hack
so far breaks changes required for dihres (3ec882b8ec64)

Change-Id: Iec63fa564c7605cdadc0417e7ddb4f6ae732c0b9