ARM: DTS: da850: fix missing #gpio-cells in gpio node

The gpio node is missing the mandatory property #gpio-cells, which is
causing runtime errors when using GPIOs e.g. with gpio-leds or gpio-keys:

"could not get #gpio-cells for /soc/gpio@1e26000"

This fixes the problem and adds the missing parameter.
The value is 2 according to the gpio-davinci.txt binding.
Signed-off-by: Petr Kulhavy <petr@barix.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

arch/arm/boot/dts/da850.dtsi

@@ -312,6 +312,7 @@ eth0: ethernet@1e20000 {
 		gpio: gpio@1e26000 {
 			compatible = "ti,dm6441-gpio";
 			gpio-controller;
+			#gpio-cells = <2>;
 			reg = <0x226000 0x1000>;
 			interrupts = <42 IRQ_TYPE_EDGE_BOTH
 				43 IRQ_TYPE_EDGE_BOTH 44 IRQ_TYPE_EDGE_BOTH