ASoC: rk817: Add module alias for rk817-codec

ASoC: rk817: Add module alias for rk817-codec

Without a module alias, autoloading the driver does not occurr
when it is built as a module.

By adding a module alias, the driver now probes fine automatically
and therefore analog audio output works as it should.

Fixes: 0d6a04da9b25 ("ASoC: Add Rockchip rk817 audio CODEC support")
Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
Link: https://lore.kernel.org/r/20211121150521.159543-1-frattaroli.nicolas@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>