floss: Fix advertising callback status type

This patch uses enum AdvertisingStatus to represent the status of
advertising callbacks, which aligns with the implementation in
libbluetooth.

Bug: 257215274
Tag: #floss
Test: build.py --target test
Test: manual test on volteer with btclient
Change-Id: I47786e242c5b75b1331b14fbe66c0a363c0f732b