ASoC: mxs: Depends on COMMON_CLK

The SAIF driver is a clock provider so specifically needs the common
clock implementedation.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>

sound/soc/mxs/Kconfig

 menuconfig SND_MXS_SOC
 	tristate "SoC Audio for Freescale MXS CPUs"
 	depends on ARCH_MXS || COMPILE_TEST
+	depends on COMMON_CLK
 	select SND_SOC_GENERIC_DMAENGINE_PCM
 	help
 	  Say Y or M if you want to add support for codecs attached to