audio: Use docstrings instead of comments in types.hal files

Converted comments into docstrings for enums and structures
in Audio HAL V7 definition.

Bug: 142480271
Test: m
Change-Id: Id5e36e7a42e2600ab69612819f8260110871c711
Merged-In: Id5e36e7a42e2600ab69612819f8260110871c711