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: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Nicolin Chen <b42378@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/sound/soc/fsl/Kconfig b/sound/soc/fsl/Kconfig
index 704e246..b7ab71f 100644
--- a/sound/soc/fsl/Kconfig
+++ b/sound/soc/fsl/Kconfig
@@ -198,6 +198,7 @@
 	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