ASoC: Tegra: Implement SPDIF CPU DAI

This is a minimal driver for the Tegra SPDIF controller.

In hardware, the SPDIF output signal is always routed to any active HDMI
display controllers, and may also be routed to external pins on Tegra
using the pinmux.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/tegra/Kconfig b/sound/soc/tegra/Kconfig
index 035d39a..c6af1fd 100644
--- a/sound/soc/tegra/Kconfig
+++ b/sound/soc/tegra/Kconfig
@@ -12,6 +12,15 @@
 	  Tegra I2S interface. You will also need to select the individual
 	  machine drivers to support below.
 
+config SND_SOC_TEGRA_SPDIF
+	tristate
+	depends on SND_SOC_TEGRA
+	default m
+	help
+	  Say Y or M if you want to add support for the SPDIF interface.
+	  You will also need to select the individual machine drivers to support
+	  below.
+
 config MACH_HAS_SND_SOC_TEGRA_WM8903
 	bool
 	help