ASoC: Fix I2C dependency for SND_FSI_AK4642 and SND_FSI_DA7210

The config option SND_FSI_AK4642 selects SND_SOC_AK4642 which in turn
enables the compilation of ak4642.c - however this codec uses I2C to
communicate with the HW.
Same applies to DA7210.

Consequently when I2C is not set, the compilation fails [1]

This patch fixes this issues, by adding a depencdency on the related HW-
controller.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>