ARM: tegra: use DT bindings for GPIO naming

There are currently many places that define the list of all Tegra GPIOs;
the DT binding header and custom Tegra-specific header file gpio.h. Fix
the redundancy by replacing everything with the DT binding header file.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>