ARM: dts: imx6sx-sabreauto: add IO expander max7310 support

i.MX6SX Sabre Auto board has two max7310 IO expander on I2C3 bus, add
support for them.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6sx-sabreauto.dts

@@ -73,6 +73,13 @@ MX6SX_PAD_GPIO1_IO02__I2C2_SCL          0x4001b8b1
 		>;
 	};
 
+	pinctrl_i2c3: i2c3grp {
+		fsl,pins = <
+			MX6SX_PAD_KEY_ROW4__I2C3_SDA            0x4001b8b1
+			MX6SX_PAD_KEY_COL4__I2C3_SCL            0x4001b8b1
+		>;
+	};
+
 	pinctrl_uart1: uart1grp {
 		fsl,pins = <
 			MX6SX_PAD_GPIO1_IO04__UART1_TX		0x1b0b1
@@ -262,3 +269,24 @@ max7322: gpio@68 {
 		#gpio-cells = <2>;
 	};
 };
+
+&i2c3 {
+	clock-frequency = <100000>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_i2c3>;
+	status = "okay";
+
+	max7310_a: gpio@30 {
+		compatible = "maxim,max7310";
+		reg = <0x30>;
+		gpio-controller;
+		#gpio-cells = <2>;
+	};
+
+	max7310_b: gpio@32 {
+		compatible = "maxim,max7310";
+		reg = <0x32>;
+		gpio-controller;
+		#gpio-cells = <2>;
+	};
+};