pinctrl: add a pincontrol driver for BCM6328

pinctrl: add a pincontrol driver for BCM6328

Add a pincontrol driver for BCM6328. BCM6328 supports muxing 32 pins as
GPIOs, as LEDs for the integrated LED controller, or various other
functions. Its pincontrol mux registers also control other aspects, like
switching the second USB port between host and device mode.

Co-developed-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Link: https://lore.kernel.org/r/20210324081923.20379-8-noltari@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>