ARM: tegra: harmony: Beginnings of audio support

This change includes everything required to enable audio on Harmony, except
those parts which rely on code not currently in Tegra's for-next branch, i.e.
except those parts which rely on merges of the Tegra I2C driver or latest
ASoC subsystem.

* Define GPIO names for audio-related GPIOs
* Set up platform data and platform device for ASoC machine driver
* Register audio-related platform devices
* Initialize audio-related clocks
* Correctly configure pinmux and GPIO enables for audio-related pins

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