audio_policy: make use of rear mic in input stream

Change-Id: I8b63dbb3c4ae2db7d9c02a72548f746ff20f5885
Raise in-call volume a bit more

Change-Id: If4b3946e7b52a24c282d4f2415d8eb54fdd2919b
Use custom generic kaylayout

Change-Id: I722e5dcee542f0868b51bb04744f4bd3be9bb2f0