arm64: a37xx: dts: add gpio head file including

Cc: Simon Glass <sjg@chromium.org>
Cc: Stefan Roese <sr@denx.de>
Signed-off-by: Ken Ma <make@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>

arch/arm/dts/armada-37xx.dtsi

@@ -46,6 +46,7 @@
 
 #include <dt-bindings/interrupt-controller/arm-gic.h>
 #include <dt-bindings/comphy/comphy_data.h>
+#include <dt-bindings/gpio/gpio.h>
 
 / {
 	model = "Marvell Armada 37xx SoC";