ASoC: adau7118: Fix Kconfig warning without CONFIG_I2C

ASoC: adau7118: Fix Kconfig warning without CONFIG_I2C

When building a kernel without CONFIG_I2C, Kconfig warns:

WARNING: unmet direct dependencies detected for REGMAP_I2C
  Depends on [n]: I2C [=n]
  Selected by [y]:
  - SND_SOC_ADAU7118_I2C [=y] && SOUND [=y] && !UML && SND [=y] && SND_SOC [=y]

Add missing I2C dependency to SND_SOC_ADAU7118_I2C to fix this.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: ca514c0f12b0 ("ASOC: Add ADAU7118 8 Channel PDM-to-I2S/TDM Converter driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20191011150042.20096-1-yuehaibing@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>