ARM: dts: omap3-overo: Add default trigger for TWL4030 LED

Commit c971ff1 'leds: leds-pwm: Defer led_pwm_set() if PWM can sleep'
fixed a crash when using a trigger with a pwm-led provided by an
external chip. Now it is safe to add the default trigger according
to board-overo.c.

Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>

arch/arm/boot/dts/omap3-overo.dtsi

@@ -21,6 +21,7 @@
 			label = "overo:blue:COM";
 			pwms = <&twl_pwmled 1 7812500>;
 			max-brightness = <127>;
+			linux,default-trigger = "mmc0";
 		};
 	};