Fix Kconfig dependency for WM97xx battery driver

It needs the WM97xx touchscreen driver to be compiled in, not as a
module.  And it cannot itself be a module, due to some unfortunate
interactions with platform data.

Reported-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>