Bluetooth: controller: Fix connection cancel deadlock

Calling bt_recv in the Bluetooth host Tx thread by the
controller implementation caused deadlock in combined host
controller builds when HCI LE Create Connection Cancel
generated the HCI LE Connection Complete or HCI LE Enhanced
Connection Complete events.

Controller's HCI implementation has been updated to place
the generated event into Rx FIFO to avoid the deadlock.

Relates to commit a59f544f ("bluetooth: controller:
Handle non-priority events correctly")

Relates to #10314.

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