ASoC: imx/mxs: remove redundant SND_PCM selection

SND_PCM is already selected by SND_SOC, there is no need for
SND_IMX_SOC and SND_MXS_SOC to select it again.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/imx/Kconfig

 menuconfig SND_IMX_SOC
 	tristate "SoC Audio for Freescale i.MX CPUs"
 	depends on ARCH_MXC
-	select SND_PCM
 	select FIQ
 	select SND_SOC_AC97_BUS
 	help

sound/soc/mxs/Kconfig

 menuconfig SND_MXS_SOC
 	tristate "SoC Audio for Freescale MXS CPUs"
 	depends on ARCH_MXS
-	select SND_PCM
 	help
 	  Say Y or M if you want to add support for codecs attached to
 	  the MXS SAIF interface.