ASoC: nau8825: disable sinc filter for high THD of ADC

This bit will enable 4th order SINC filter.
=1, filter will enable;  but it consumes higher power.
=0, the sinc filter is disable, and it should always keep 0 value to
get high THD.

Therefor, disable the filter when codec initiation for better
performance when recording.

Signed-off-by: John Hsu <KCHSU0@nuvoton.com>
Signed-off-by: Mark Brown <broonie@kernel.org>