gpio: tegra: Make of_device_id compatible data to constant

The data member of the of_device_id is the constant type
and hence all static structure which is used for this
initialisation as static.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Suggested-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>