ASoC: dapm: Support second register for DAPM control updates

To support double channel shared controls split across 2 registers, one
for each channel, we must be able to update both registers together.

Add a second set of register fields to struct snd_soc_dapm_update, and
update the DAPM control writeback (put) callbacks to support this.

For codecs that use custom events which call into DAPM to do updates,
also clear struct snd_soc_dapm_update before using it, so the second
set of fields remains clean.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dapm.h

@@ -615,6 +615,10 @@ struct snd_soc_dapm_update {
 	int reg;
 	int mask;
 	int val;
+	int reg2;
+	int mask2;
+	int val2;
+	bool has_second_set;
 };
 
 struct snd_soc_dapm_wcache {