ASoC: ep93xx: i2s: Make it individually selectable

This is necessary to replace EDB93XX specific SoC audio driver with generic
"simple-audio-card".

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20230410223902.2321834-4-alexander.sverdlin@gmail.com


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