p1-common: audio: add audio submix support

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Ia188cc3537bc93edb8d24f9352dee209701298ca
p1-common: audio: fix audio sampling rates

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Ic84f51b39b7481e61af734dcf6fc72ddd94bbd6e