ASoC: SOF: acpi led support for switch controls

ASoC: SOF: acpi led support for switch controls

Currently sof doesn't support acpi leds with mute switches. So implement
acpi leds following quite shamelessly existing HDA implementation by
Takashi Iwai.

Mute leds can be enabled in topology by adding led and direction token
in switch control private data.

Signed-off-by: Jaska Uimonen <jaska.uimonen@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191008164443.1358-10-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>