ASoC: rt5640: Add RL6231 class device shared support for RT5640, RT5645 and RT5651

The patch adds the RL6231 class device shared support for RT5640, RT5645 and
RT5651. The function of the DMIC clock calculation can be shared by RL6231
shared support.

Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --cc sound/soc/codecs/Kconfig
Simple merge

diff --cc sound/soc/codecs/Makefile
Simple merge

diff --cc sound/soc/codecs/rl6231.c
Simple merge

diff --cc sound/soc/codecs/rl6231.h
Simple merge

diff --cc sound/soc/codecs/rt5640.c
Simple merge

diff --cc sound/soc/codecs/rt5645.c
Simple merge

diff --cc sound/soc/codecs/rt5651.c
Simple merge