ASoC: nau8540: reset state machine for channel phase sync

The four channel ADCs in NAU85L40 have difference control registers,
it is hard to synchronous these four channels without correct sequence.
The phase difference will not be a constant and not to conjecture easily.
It may be 2.55 degree, or more ,or less.
Intended to prevent phase difference of channels, the solution as follows:
(1)Channel_Sync need to be enabled.
(2)Do soft reset without affecting register when recording done.

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