Previously, snd-soc-tegra-harmony internally instantiated a platform device
object whenever the module was loaded. Instead, switch to a more typical model
where arch/arm/mach-tegra defines a platform device, and snd-soc-tegra-harmony
acts as a driver for such a platform device.

Define a new struct tegra_harmony to store driver data in the future.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Acked-by: NLiam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>