arm: mvebu: enable gpio expander over i2c on Mirabox platform

The Globalscale Mirabox platform can be connected to the JTAG/GPIO box
through the Multi-IO port. The GPIO box use the NXP PCA9505 I/O port
expansion IC to provide 40-bit parallel input/output GPIOs. This patch
enable the use of this expander on the Mirabox.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-370-mirabox.dts

@@ -70,5 +70,16 @@ usb@d0050000 {
 		usb@d0051000 {
 			status = "okay";
 		};
+
+		i2c@d0011000 {
+			status = "okay";
+			clock-frequency = <100000>;
+			pca9505: pca9505@25 {
+				compatible = "nxp,pca9505";
+				gpio-controller;
+				#gpio-cells = <2>;
+				reg = <0x25>;
+			};
+		};
 	};
 };