ril: voice routing: better timing for better quality

 * The voice quality is quite usable now, maybe more improvements are possible
 * Using the right timings (period_size) is crucial
  - libtinyalsa changes the specified period_size, so we have to work arround it
  - 44100 Hz (gta04) and 8000 Hz (modem) sound devices need different period_size,
    but those have to fit each other, so they have the same latency (i.e. 33,3ms)

Signed-off-by: Lukas Märdian <lukas@goldelico.com>