ASoC: mt6358: Fix event generation for wake on voice stage 2 switch

ASoC: mt6358: Fix event generation for wake on voice stage 2 switch

ALSA control put() operations should return 0 if the value changed so that
events can be generated appropriately for userspace but the custom control
for wake on voice stage 2 doesn't do this, fix it.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230224-asoc-mt6358-quick-fixes-v1-1-747d9186be4b@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>