ASoC: rsnd: use array for 44.1kHz/48kHz rate handling

ADG need to know output rate of 44.1kHz/48kHz.
It is using single variable for each, but this patch changes
it to array. Nothing is changed by this patch.

This is prepare for R-Car Gen4 support.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87tu065em3.wl-kuninori.morimoto.gx@renesas.com


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