ARM: at91/dt: add Calao DAB-MMX daugther board support for USB-A9G20

http://www.calao-systems.com/articles.php?lng=en&pg=6099

this daughter board add the following device:
 - Micro-SD socket
 - TTL 3V3 - (Tx/Rx/RTS/CTS)
 - I2C port
 - 0.96" Serial OLED Display Module (over UART)
 - MP3 decoder with Micro & Speakers
 - 4x PB, 4x Leds (Blue), 3x Leds (Green, Orange, Red)

for now we add only the 2 UARTs, 4 Buttons, 7 leds and i2c via DT

used_led1 will not be re-add via DT as it's used by the motherboard too
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

arch/arm/boot/dts/usb_a9g20-dab-mmx.dtsi

+/*
+ * calao-dab-mmx.dtsi - Device Tree Include file for Calao DAB-MMX Daughter Board
+ *
+ * Copyright (C) 2011 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
+ *
+ * Licensed under GPLv2.
+ */
+
+/ {
+	ahb {
+		apb {
+			usart1: serial@fffb4000 {
+				status = "okay";
+			};
+
+			usart3: serial@fffd0000 {
+				status = "okay";
+			};
+		};
+	};
+
+	i2c-gpio@0 {
+		status = "okay";
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		user_led1 {
+			label = "user_led1";
+			gpios = <&pioB 20 1>;
+		};
+
+/*
+* led already used by mother board but active as high
+*		user_led2 {
+*			label = "user_led2";
+*			gpios = <&pioB 21 1>;
+*		};
+*/
+		user_led3 {
+			label = "user_led3";
+			gpios = <&pioB 22 1>;
+		};
+
+		user_led4 {
+			label = "user_led4";
+			gpios = <&pioB 23 1>;
+		};
+
+		red {
+			label = "red";
+			gpios = <&pioB 24 1>;
+		};
+
+		orange {
+			label = "orange";
+			gpios = <&pioB 30 1>;
+		};
+
+		green {
+			label = "green";
+			gpios = <&pioB 31 1>;
+		};
+	};
+
+	gpio_keys {
+		compatible = "gpio-keys";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		user_pb1 {
+			label = "user_pb1";
+			gpios = <&pioB 25 1>;
+			linux,code = <0x100>;
+		};
+
+		user_pb2 {
+			label = "user_pb2";
+			gpios = <&pioB 13 1>;
+			linux,code = <0x101>;
+		};
+
+		user_pb3 {
+			label = "user_pb3";
+			gpios = <&pioA 26 1>;
+			linux,code = <0x102>;
+		};
+
+		user_pb4 {
+			label = "user_pb4";
+			gpios = <&pioC 9 1>;
+			linux,code = <0x103>;
+		};
+	};
+};