ASoC: wm2000: remove unused #include <linux/version.h>

Remove unused #include <linux/version.h>('s) in
  sound/soc/codecs/wm2000.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>