dt-bindings: pinctrl: at91-pio4: Add push-pull support

Add generic push-pull support for pio4 driver.

Signed-off-by: Ryan Wanner <Ryan.Wanner@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/048a41d1dcb3da0e845986a73eaac61a54c69269.1684313910.git.Ryan.Wanner@microchip.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>