gpio: tegra: Get rid of all file scoped global variables

Move the file scoped multiple global variable from Tegra GPIO
driver to the structure and make this as gpiochip data which
can be referred from GPIO chip callbacks.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>