ASoC: tegra: add tegra30-i2s driver

This provides an ASoC DAI interface for Tegra 30's I2S controller.

Includes a squashed bugfix from Sumit Bhattacharya <sumitb@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Documentation/devicetree/bindings/sound/nvidia,tegra30-i2s.txt

+NVIDIA Tegra30 I2S controller
+
+Required properties:
+- compatible : "nvidia,tegra30-i2s"
+- reg : Should contain I2S registers location and length
+- nvidia,ahub-cif-ids : The list of AHUB CIF IDs for this port, rx (playback)
+  first, tx (capture) second. See nvidia,tegra30-ahub.txt for values.
+
+Example:
+
+i2s@70002800 {
+	compatible = "nvidia,tegra30-i2s";
+	reg = <0x70080300 0x100>;
+	nvidia,ahub-cif-ids = <4 4>;
+};