ipq40xx: fix missing include

This patch fixes a blunder of mine. The include needed
for LED_COLOR_ID_BLUE property is missing.

This caused the builds to fail with:
|Error: arch/arm/boot/dts/qcom-ipq4019-r619ac.dtsi:91.13-14 syntax error
|FATAL ERROR: Unable to parse input tree

Fixes: 12d33d3 ("ipq40xx: add support for P&W R619AC (aka G-DOCK 2.0)")
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-r619ac.dtsi

@@ -4,6 +4,7 @@
 #include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/input/input.h>
 #include <dt-bindings/soc/qcom,tcsr.h>
+#include <dt-bindings/leds/common.h>
 
 / {
 	chosen {