ASoC: codecs: Fix duplicate included sound/soc.h

Clean up the following includecheck warnings:

./sound/soc/codecs/wcd938x.c: sound/soc.h is included more than once.
./sound/soc/codecs/wcd938x-sdw.c: sound/soc.h is included more than
once.

No functional change.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/1623822667-130511-1-git-send-email-jiapeng.chong@linux.alibaba.com


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