ASoC: ak4613: disable asymmetric audio interface format

Asymmetric audio interface formats exist in ak4613 by same
register settings.

	Capture		Playback
	24bit LEFT_J	16bit RIGHT_J
	24bit LEFT_J	20bit RIGHT_J
	24bit LEFT_J	24bit RIGHT_J
	24bit LEFT_J	24bit LEFT_J
	24bit I2S	24bit I2S

These asymmetric formats makes driver / behavior difficult.
It is not HW limitation, but SW limitation. To makes code reading
easy, this patch removes asymmetric format support.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>