le_audio: Correct Broadcast dump format

For better readiness of mDevice and some space between event logger and
device context an additional white lines should be introduced.

Tag: #feature
Test: atest BassClientServiceTest
Test: atest BassClientStateMachineTest
Bug: 298079825
Change-Id: If259372f0b4d160ce78be7eed5f229d1f11cfc12