atv_demod: modify atv demod code [1/1]

atv_demod: modify atv demod code [1/1]

PD#SWPL-2295

Problem:
1.modify atv demod code for coverity.
2.add ntsc-m ring filter for t962x2.
3.merge code optimization from android l.
4.add tuner compatible info in dts for tuner debug.

Solution:
1.modify atv demod code for coverity.
2.add ntsc-m ring filter for t962x2.
3.merge code optimization from android l.
4.add tuner compatible info in dts for tuner debug.

Verify:
verified by einstein

Change-Id: I9696aa628315ee11f0c9dd279c7cc03797f04331
Signed-off-by: nengwen.chen <nengwen.chen@amlogic.com>