ARM: shmobile: armadillo: dts: Add PWM backlight enable GPIO

The Armadillo 800 EVA panel module has a backlight enable signal
connected to GPIO 61. Report this in the backlight DT node.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7740-armadillo800eva-reference.dts

@@ -96,6 +96,7 @@ backlight {
 		pinctrl-0 = <&backlight_pins>;
 		pinctrl-names = "default";
 		power-supply = <&reg_5p0v>;
+		enable-gpios = <&pfc 61 GPIO_ACTIVE_HIGH>;
 	};
 
 	sound {