ASoC: samsung: SMDK_WM8580_PCM needs REGMAP_I2C

This adds a missing dependency for SND_SOC_SMDK_WM8580_PCM to
require REGMAP_I2C to be enabled, avoiding possible build
erorrs.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xia Kaixu <kaixu.xia@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>