ARM: dts: omap3-tobi: Correct polarity for GPIO LED

The LED is active low, not active high.
Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>

arch/arm/boot/dts/omap3-tobi.dts

@@ -20,7 +20,7 @@ leds {
 		compatible = "gpio-leds";
 		heartbeat {
 			label = "overo:red:gpio21";
-			gpios = <&gpio1 21 GPIO_ACTIVE_HIGH>;
+			gpios = <&gpio1 21 GPIO_ACTIVE_LOW>;
 			linux,default-trigger = "heartbeat";
 		};
 	};