powerpc/wii.dts: Add ngpios property

The Hollywood GPIO controller supports 32 GPIOs, but on the Wii, only 24
are used.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/boot/dts/wii.dts

@@ -176,6 +176,7 @@ GPIO: gpio@d8000c0 {
 			compatible = "nintendo,hollywood-gpio";
 			reg = <0x0d8000c0 0x40>;
 			gpio-controller;
+			ngpios = <24>;
 
 			/*
 			 * This is commented out while a standard binding