dt-bindings: pinctrl: meson: add output support in pinconf

add support for the pinconf DT property output-enable, output-disable,
output-low and output-high in the meson pinctrl driver.
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/meson,pinctrl.txt

@@ -47,9 +47,15 @@ Required properties for pinmux nodes are:
 Required properties for configuration nodes:
  - pins: a list of pin names
 
-Configuration nodes support the generic properties "bias-disable",
-"bias-pull-up" and "bias-pull-down", described in file
-pinctrl-bindings.txt
+Configuration nodes support the following generic properties, as
+described in file pinctrl-bindings.txt:
+ - "bias-disable"
+ - "bias-pull-up"
+ - "bias-pull-down"
+ - "output-enable"
+ - "output-disable"
+ - "output-low"
+ - "output-high"
 
 Optional properties :
  - drive-strength-microamp: Drive strength for the specified pins in uA.