realtek: rtl838x: Switch GS1900 rtl8231 driver

realtek: rtl838x: Switch GS1900 rtl8231 driver

Update the devicetree files to switch the GS1900 devices over to the new
pinctrl and GPIO driver.

This may fix issues caused by bad RMW behaviour on the GPIO data lines,
or glitches due to setting the pin direction before the pin level.

Although the driver support retaining GPIO state after a warm boot, the
bootloader appears to apply a default configuration on boot, which may
cause an interrupt in PoE-PSE support.

Signed-off-by: Sander Vanheule <sander@svanheule.net>