ASoC: rsnd: tidyup ADINR function name

Renesas sound IP (= SSIU/SRC/CTU/MIX/DVC) have ADINR
(= Audio Information Register), but some of them (= SSIU/SRC/DVC)
are for audio data bits, some of them (= CTU/MIX) are for audio data
channels.
Current rsnd driver is supporting SSIU/SRC/DVC, and these ADINR were
for bits. This patch rename rsnd_get_adinr() to rsnd_get_adinr_bit(),
and we will have rsnd_get_adinr_chan() for CTU/MIX.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>