ASoC: tegra: simplify Kconfig dependencies

The Tegra ASoC machine drivers only depend on Tegra architecture support
to compile, not specific board support. Remove Kconfig dependencies on
any particular board. This is required since Kconfig options for boards
are going away given the migration to device tree.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>