ASoC: Intel: don't select RT5640 if !I2C

The rt5640 driver won't compile without I2C enabled. Hence, the Intel
Haswell and Baytrail+RT5640 ASoC drivers must also depend on I2C, since
these select RT5640.

This solves:
sound/soc/codecs/rt5640.c:2220:1: warning: data definition has no type or storage class [enabled by default]
sound/soc/codecs/rt5640.c:2220:1: error: type defaults to ‘int’ in declaration of ‘module_i2c_driver’ [-Werror=implicit-int]
sound/soc/codecs/rt5640.c:2220:1: warning: parameter names (without types) in function declaration [enabled by default]
sound/soc/codecs/rt5640.c:2210:26: warning: ‘rt5640_i2c_driver’ defined but not used [-Wunused-variable]

Reported-by: Jim Davis <jim.epost@gmail.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>