arm64: dts: rockchip: add new watchdog compatible to rk3399.dtsi

The watchdog compatible strings are suppose to be SoC orientated.
In the more recently added Rockchip rk3399.dtsi file only
the fallback string "snps,dw-wdt" is used, so add the new
compatible string:

"rockchip,rk3399-wdt", "snps,dw-wdt"

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/watchdog/snps,dw-wdt.yaml
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20201218120534.13788-7-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399.dtsi

@@ -1531,7 +1531,7 @@ tcphy1_usb3: usb3-port {
 	};
 
 	watchdog@ff848000 {
-		compatible = "snps,dw-wdt";
+		compatible = "rockchip,rk3399-wdt", "snps,dw-wdt";
 		reg = <0x0 0xff848000 0x0 0x100>;
 		clocks = <&cru PCLK_WDT>;
 		interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH 0>;