ASoC: cirrus: tlv320aic23 needs I2C

The tlv320aic23 codec is selected by the ep93xx snapper platform,
which are missing a dependency on I2C, and that can result in this
build error, as found during randconfig builds:

.../codecs/tlv320aic23-i2c.c: In function 'tlv320aic23_i2c_probe':
.../codecs/tlv320aic23-i2c.c:27:2: error: implicit declaration of function 'i2c_check_functionality' [-Werror=implicit-function-declaration]
  if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  ^

This adds the missing dependency.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/cirrus/Kconfig

@@ -16,7 +16,7 @@ config SND_EP93XX_SOC_AC97
 
 config SND_EP93XX_SOC_SNAPPERCL15
         tristate "SoC Audio support for Bluewater Systems Snapper CL15 module"
-        depends on SND_EP93XX_SOC && MACH_SNAPPER_CL15
+        depends on SND_EP93XX_SOC && MACH_SNAPPER_CL15 && I2C
         select SND_EP93XX_SOC_I2S
         select SND_SOC_TLV320AIC23_I2C
         help