ARM: dt: tegra: Enable audio on WM8903 boards, disable others

Add complete bindings to instantiate and configure the codec and
top-level audio complex on all currently supported boards using the
Tegra+WM8903 audio driver.

On those boards, disable the I2S2 controller since it isn't used.

On boards not using the WM8903 codec, disable all the audio devices;
they can be re-enabled once the relevant codec and ASoC machine drivers
have been ported to device-tree.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>