alsa_sound: Add hdmi audio sink capability discovery

- Add hdmi sink capabilities parsing utility to support
  multi-channel output configuration.
- Update getParameters to calculate supported channels by
  hdmi sink.
- Update alsa_default to calculate channel count to set control
  option.

Bug: 7156174
Change-Id: Iabb9844c1e5a8b7aa7f168992f8beef79b7df8d2
Signed-off-by: Iliyan Malchev <malchev@google.com>