Convert mask types from uint32_t to enum type

This applies to the following types:

- audio_gain_mode_t;
- audio_flags_mask_t;
- audio_channel_representation_t;
- audio_channel_mask_t;
- audio_devices_t.

Enum types are distinct thus proper overloading on the type
is possible in C++. Also, assignments to enum types are
less prone to errors.

Bug: 169889714
Test: basic audio functionality
Change-Id: I8f1e6fa2bbad8900fdae66f01ac70c75953fd62c
Merged-In: I8f1e6fa2bbad8900fdae66f01ac70c75953fd62c
1 file changed