ASoC: pcm512x: Split out bus drivers

Move to the new style of defining the bus interfaces in separate modules
in order to simplify dependencies.

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/pcm512x-i2c.c
Simple merge

diff --cc sound/soc/codecs/pcm512x-spi.c
Simple merge

diff --cc sound/soc/codecs/pcm512x.c
Simple merge

diff --cc sound/soc/codecs/pcm512x.h
Simple merge