Remove unused #include <linux/version.h>('s) in
  sound/soc/codecs/ad1836.c
  sound/soc/codecs/ad1938.c
  sound/soc/codecs/wm8974.c
Signed-off-by: NHuang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>