ARM: Tegra: Seaboard board updates for audio

* Initialize clock tree for audio
* Add GPIO base definitions
* Add audio GPIO definitions
* Define platform data for WM8903 and ASoC machine driver
* Add special case for Kaen to handle HP_MUTE GPIO
* Register platform devices for audio
* Update pinmux to cater for new GPIOs used for audio

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