pinctrl: tps6594: Add driver for TPS6594 pinctrl and GPIOs

TI TPS6594 PMIC has 11 GPIOs which can be used
for different functions.

This patch adds a pinctrl and GPIO drivers in
order to use those functions.

Signed-off-by: Esteban Blanc <eblanc@baylibre.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20231108104124.2818275-1-eblanc@baylibre.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>