ASoC: rsnd: indicate register name for debug

Current rsnd driver is indicating how to use regmap debug method
on gen.c comment area.
regmap debug method indicates address and value, but rsnd driver is
using too many IPs (SSI/SSIU/SRC/CTU/MIX/DVC/CMD), and address.
Thus, we would like to know more useful information for debugging.
This patch indicates address name for debugging.

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