Bluetooth: Controller: Fix missing radio tmr status reset

Fix missing radio tmr status reset on radio_disable call,
without this which disables PPI/DPPI caused under race
conditions the radio to transition into Tx or Rx state and
put the Controller's state out of sync with the Radio
peripherals internal state. The symptoms being that the
Central role was not transmitting in the next interval;
also, caused the defer iterations to reach maximum events
being enqueued in the pipeline, and manifesting as large
CPU overheads in redundant prepare of deferred events.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>