drivers: gpio: rv32m1: configure pin mux as GPIO
drivers: gpio: rv32m1: configure pin mux as GPIO

Set the PCR[MUX] field to kPORT_MuxAsGpio as part of configuring a GPIO
pin. This removes the need to explicitly call pinmux_pin_set() in board
code.

Signed-off-by: Henrik Brix Andersen <a076b11c2cc63ccdc903dbe182e1eecc3cbbc094@brixandersen.dk>

galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr