gpio: dwapb: correct gpio-cells in binding document

The example uses gpio-cells = 1 while it should be two (it is even
mentioned in the text above).

Cc: devicetree@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/snps-dwapb-gpio.txt

@@ -41,7 +41,7 @@ gpio: gpio@20000 {
 	porta: gpio-controller@0 {
 		compatible = "snps,dw-apb-gpio-port";
 		gpio-controller;
-		#gpio-cells = <1>;
+		#gpio-cells = <2>;
 		snps,nr-gpios = <8>;
 		reg = <0>;
 		interrupt-controller;
@@ -53,7 +53,7 @@ gpio: gpio@20000 {
 	portb: gpio-controller@1 {
 		compatible = "snps,dw-apb-gpio-port";
 		gpio-controller;
-		#gpio-cells = <1>;
+		#gpio-cells = <2>;
 		snps,nr-gpios = <8>;
 		reg = <1>;
 	};