ASoC: rt9120: Add rt9210 audio amplifier support

Add Richtek rt9120 audio amplifier support.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1634088519-995-3-git-send-email-u0084500@gmail.com


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