MS uplink power control is required in pretty much any BTS, and we
cannot assume that they PHY / L1 will always take care of it by
itself. So the correspondign code is moved to common/power_control.c
and called from the generic part of L1SAP.
The corresponding VTY paramter has been moved from the sysmobts-specific
trx VTY node to the common BTS VTY node.