pinctrl-tegra: Restore SFSEL bit when freeing pins

pinctrl-tegra: Restore SFSEL bit when freeing pins

Each pin can be configured as a Special Function IO (SFIO) or GPIO,
where the SFIO enables the pin to operate in alternative modes such as
I2C, SPI, etc.

The current implementation sets all the pins back to SFIO mode
even if they were initially in GPIO mode. This can cause glitches
on the pins when pinctrl_gpio_free() is called.

Avoid these undesired glitches by storing the pin's SFIO/GPIO
state on GPIO request and restoring it on GPIO free.

Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
Link: https://lore.kernel.org/20250305104939.15168-2-pshete@nvidia.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>