ARM: tegra: Use generated pinmux for Beaver board

Replace the current incomplete pinmux setup with a proper one generated
using the tegra pinmux scripts.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>