ASoC: tegra: introduce separate Kconfig variable for DAS driver

This is mainly for symmetry with a future Tegra30 driver, where the
equivalent of the DAS (the AHUB) is useful separately from the I2S driver.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/tegra/Kconfig

@@ -4,9 +4,18 @@ config SND_SOC_TEGRA
 	help
 	  Say Y or M here if you want support for SoC audio on Tegra.
 
+config SND_SOC_TEGRA_DAS
+	tristate "Tegra Digital Audio Switch driver"
+	depends on SND_SOC_TEGRA
+	help
+	  Say Y or M if you want to add support for the Tegra DAS module.
+	  You will also need to select the individual machine drivers to
+	  support below.
+
 config SND_SOC_TEGRA_I2S
 	tristate
 	depends on SND_SOC_TEGRA
+	select SND_SOC_TEGRA_DAS
 	help
 	  Say Y or M if you want to add support for codecs attached to the
 	  Tegra I2S interface. You will also need to select the individual

sound/soc/tegra/Makefile

@@ -6,7 +6,7 @@ snd-soc-tegra-spdif-objs := tegra_spdif.o
 snd-soc-tegra-utils-objs += tegra_asoc_utils.o
 
 obj-$(CONFIG_SND_SOC_TEGRA) += snd-soc-tegra-utils.o
-obj-$(CONFIG_SND_SOC_TEGRA) += snd-soc-tegra-das.o
+obj-$(CONFIG_SND_SOC_TEGRA_DAS) += snd-soc-tegra-das.o
 obj-$(CONFIG_SND_SOC_TEGRA) += snd-soc-tegra-pcm.o
 obj-$(CONFIG_SND_SOC_TEGRA_I2S) += snd-soc-tegra-i2s.o
 obj-$(CONFIG_SND_SOC_TEGRA_SPDIF) += snd-soc-tegra-spdif.o