Implement new 'raw' input type for E1 timeslots

In the past, the A-bis E1 input system only unederstood LAPD signalling
time-slots and trau-slots with 16kBps sub-slots.  This adds the notion
of a 'raw' transparent 64kBps slot, without any furthe de-multiplexing
nor any HLDC inside.

Change-Id: I0c25c2688eddd0c55c15b280a8c6e8a49629516b
4 files changed