ASoC: fsl_spdif: Select regmap-mmio

The S/PDIF driver needs regmap so select it to make sure it gets
included in the build.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Acked-by: NNicolin Chen <b42378@freescale.com>
Signed-off-by: NMark Brown <broonie@linaro.org>

sound/soc/fsl/Kconfig

@@ -198,6 +198,7 @@ config SND_SOC_IMX_SPDIF
 	select SND_SOC_IMX_PCM_DMA
 	select SND_SOC_FSL_SPDIF
 	select SND_SOC_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