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

Documentation/devicetree/bindings/pinctrl/atmel,at91-pio4-pinctrl.txt

@@ -37,7 +37,8 @@ right representation of the pin.
 Optional properties:
 - GENERIC_PINCONFIG: generic pinconfig options to use:
 	- bias-disable, bias-pull-down, bias-pull-up, drive-open-drain,
-	  input-schmitt-enable, input-debounce, output-low, output-high.
+	 drive-push-pull input-schmitt-enable, input-debounce, output-low,
+	 output-high.
 	- for microchip,sama7g5-pinctrl only:
 		- slew-rate: 0 - disabled, 1 - enabled (default)
 - atmel,drive-strength: 0 or 1 for low drive, 2 for medium drive and 3 for