ARM: apx4devkit: remove AUART3

AUART3 is not available anymore. Pins are used as GPIOs.
Signed-off-by: NLauri Hintsala <lauri.hintsala@bluegiga.com>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/apx4devkit.dts

@@ -149,12 +149,6 @@
 				pinctrl-0 = <&auart2_2pins_a>;
 				status = "okay";
 			};
-
-			auart3: serial@80070000 {
-				pinctrl-names = "default";
-				pinctrl-0 = <&auart3_2pins_a>;
-				status = "okay";
-			};
 		};
 	};