ARM: at91: sam9g20 add i2c DT support

For now on use i2c-gpio driver on the same pin as the hardware IP.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/boot/dts/at91sam9g20.dtsi

@@ -189,4 +189,17 @@ &pioC 14 0
 			status = "disabled";
 		};
 	};
+
+	i2c@0 {
+		compatible = "i2c-gpio";
+		gpios = <&pioA 23 0 /* sda */
+			 &pioA 24 0 /* scl */
+			>;
+		i2c-gpio,sda-open-drain;
+		i2c-gpio,scl-open-drain;
+		i2c-gpio,delay-us = <2>;	/* ~100 kHz */
+		#address-cells = <1>;
+		#size-cells = <0>;
+		status = "disabled";
+	};
 };