gpio: tegra186: Check GPIO pin permission before access.

This change checks if we have the necessary permission to
access the GPIO. For devices that have support for virtualisation
we need to check both the TEGRA186_GPIO_VM_REG and the
TEGRA186_GPIO_SCR_REG registers. For device that do not have
virtualisation support for GPIOs we only need to check the
TEGRA186_GPIO_SCR_REG register.

Signed-off-by: Manish Bhardwaj <mbhardwaj@nvidia.com>
Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>