drivers: pinctrl: nrf: Add support for PWM, QDEC, and QSPI peripherals

Add support for configuring pins to be used by the nRF PWM, QDEC, and
QSPI peripherals.
A new custom property "nordic,invert" is added to the pin configuration
group binding to allow configuring PWM channel outputs as inverted.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>