ASoC: SOF: control: return true when kcontrol values change

ASoC: SOF: control: return true when kcontrol values change

All the kcontrol put() functions are currently returning 0 when
successful. This does not go well with alsamixer as it does
not seem to get notified on SND_CTL_EVENT_MASK_VALUE callbacks
when values change for (some of) the sof kcontrols.
This patch fixes that by returning true for volume, switch
and enum type kcontrols when values do change in put().

Signed-off-by: Dragos Tarcatu <dragos_tarcatu@mentor.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191018123806.18063-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>