atv_demod: fix atv non standard signal audio handle [1/1]

atv_demod: fix atv non standard signal audio handle [1/1]

PD#TV-6044, PD#TV-6047

Problem:
ATV sound output has noise when input non standard signal.

Solution:
1.fix atv non standard signal audio handle.
2.remove atv audio source selection in audio module.
3.atv demod selects audio source according to signal.
4.atv demod version: V2.12.

Verify:
Verified by x301

Change-Id: Ie0fce492f1ce7f5a5866d8674c95c97ee32452c0
Signed-off-by: nengwen.chen <nengwen.chen@amlogic.com>