ASoC: soc-core: add soc_playback_digital_mute()

snd_soc_suspend() and soc_resume_deferred() are calling
same snd_soc_dai_digital_mute() with same logic with different parameter.
This patch adds new soc_playback_digital_mute() and share the code.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87k0u7ekfv.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>