realtek: ensure output drivers are enabled in RTL8231

realtek: ensure output drivers are enabled in RTL8231

The bootloader can leave the GPIO expander in a state which doesn't have
output drivers enabled so GPIOs will properly work for input but output
operations will have no effect.

To avoid disrupting the boot in case the bootloader left direction and
data registers in an inconsistent state (e.g. pulling SoC's reset to 0)
reconfigure everything as input.

Reviewed-by: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Paul Fertser <fercerpav@gmail.com>