Bluetooth: Controller: Fix directed adv connection setup stall

When directed advertising and continuous scanning are
simultaneously active, and a connection request is received
by the directed advertising state then the connection was
not established due to the done event not being generated.

Done event from the directed advertising state was not
generated because the prepare pipeline only had resume
event which does not get scheduled when there is prepare
event of the continuous scan state.

The fix is to explicitly abort all pending prepare and
resume event in the pipeline for the directed advertising
state when connection request is received.

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