ASoC: rsnd: make sure SSI parent/child uses same number of sound channel.

SSI parent/child need to use same number of sound data channel
if these are sharing clock/ws pin. this patch makes it sure.

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