Bluetooth: controller: conformance testcase failures

[cvinayak]

Describe the bug
All the conformance testcases related to advertising enable (except directed advertising) fail, due to missing advertising PDU transmission on-air.

To Reproduce
Steps to reproduce the behavior:

1. Update samples/bluetooth/hci_uart/prj.conf accordingly to match Bluetooth ICS requirements
2. mkdir build; cd build
3. cmake -GNinja -DBOARD=nrf52dk_nrf52832 ../samples/bluetooth/hci_uart
4. ninja
5. ninja flash
6. Use the board to run, hci uart interface, conformance tests

Expected behavior
Conformance testcases pass.

Impact
showstopper

Logs and console output
Internal logs.

Environment (please complete the following information):

• OS: Linux
• Toolchain: Zephyr SDK 0.11.2
• Commit SHA or Version used: 8f8ec5f

Additional context
NA