TRX: Set ciphering to an initial state when activating channel
TRX: Set ciphering to an initial state when activating channel

Handover and assignment may activate channels with ciphering already set,
so we need to tell scheduler to enable/disable ciphering and set the
correct cipher state.

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts