Bluetooth: Controller: Fix ticker ops count for extended initiator

Increase the ticker operations count in ULL high context
when Extended Advertising Connection Establishment on Coded
PHY is supported.

This fixes assertion in Controller when initiating a
connection on Coded PHY, wherein two scan instance ticker,
one window stop ticker, and a new connection instance
ticker operations needs to be enqueued.

Relates to commit a6b8eba7 ("Bluetooth: controller:
Implement disabling the other PHY initiator").

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