ASoC: max98357a: move control of SD_MODE back to DAI ops

Partially reverts commit 128f825a ("ASoC: max98357a: move control
of SD_MODE to DAPM").

In order to have mute control of max98357 from machine drivers, commit
128f825a ("ASoC: max98357a: move control of SD_MODE to DAPM")
moves the control of SD_MODE from DAI ops to DAPM events.  However, pop
noise has been observed on rk3399-gru-kevin boards due to this commit.

The commit 128f825a caused sequence of DAI clocks and SD_MODE
changed on rk3399-gru-kevin boards.

With the commit 128f825a

:
- SD_MODE will be set to 1 before DAI clocks start.
- SD_MODE will be set to 0 after DAI clocks stop.
As a result, pop noise.

Moves the control of SD_MODE back to DAI ops.  In the meantime, uses an
additional flag in DAPM event to provide chance of mute control for
machine drivers.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Tested-By: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Link: https://lore.kernel.org/r/20200721114232.2812254-1-tzungbi@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>