Bluetooth: Controller: Dont prioritize ticker slot window that yield

Do not use lazy value to prioritize ticker with ticks slot
window that yield to other tickers. Primary channel PDUs
use ticks slow window to nudge themself after an
overlapping ticker within the ticks slot window, but such
ticker may be skipped to next interval. At the next
interval if they again overlap with other tickers then
lazy value shall not be used to prioritize but rather
continue to yield again. This is required to avoid BIG
events from being skipped.

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