ARM: dts: imx6qdl-apf6dev: add RTC support

Add support of MCP79400 RTC.
Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6qdl-apf6dev.dtsi

@@ -169,6 +169,11 @@ codec: sgtl5000@a {
 		VDDA-supply = <&reg_3p3v>;
 		VDDIO-supply = <&reg_3p3v>;
 	};
+
+	rtc@6f {
+		compatible = "microchip,mcp7940x";
+		reg = <0x6f>;
+	};
 };
 
 &i2c3 {