ASoC: fsl: make sure the regmap-mmio is actually enabled

Since the Freescale SAI, ESAI and SPDIF are using the regmap-mmio,
there needs a select of REGMAP_MMIO in the Kconfig to ensure that
regmap-mmio is actually enabled.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/fsl/Kconfig

 config SND_SOC_FSL_SAI
 	tristate
+	select REGMAP_MMIO
 	select SND_SOC_GENERIC_DMAENGINE_PCM
 
 config SND_SOC_FSL_SSI
@@ -7,9 +8,11 @@ config SND_SOC_FSL_SSI
 
 config SND_SOC_FSL_SPDIF
 	tristate
+	select REGMAP_MMIO
 
 config SND_SOC_FSL_ESAI
 	tristate
+	select REGMAP_MMIO
 
 config SND_SOC_FSL_UTILS
 	tristate
@@ -204,7 +207,6 @@ config SND_SOC_IMX_SPDIF
 	tristate "SoC Audio support for i.MX boards with S/PDIF"
 	select SND_SOC_IMX_PCM_DMA
 	select SND_SOC_FSL_SPDIF
-	select REGMAP_MMIO
 	help
 	  SoC Audio support for i.MX boards with S/PDIF
 	  Say Y if you want to add support for SoC audio on an i.MX board with