ARM: dts: imx6ull: add wdog3

The i.MX6ULL has a WDOG3 located at start address 0x021E0000 in the
AIPS-2 memory region [1].

[1] i.MX 6ULL Applications Processor Reference Manual, Rev. 1, 11/2017,
    Table 2-3. AIPS-2 memory map, p. 178

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>

arch/arm/dts/imx6ull.dtsi

@@ -1026,6 +1026,14 @@
 				status = "disabled";
 			};
 
+			wdog3: wdog@021e4000 {
+				compatible = "fsl,imx6ul-wdt", "fsl,imx21-wdt";
+				reg = <0x021e4000 0x4000>;
+				interrupts = <GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>;
+				clocks = <&clks IMX6UL_CLK_WDOG3>;
+				status = "disabled";
+			};
+
 			uart2: serial@021e8000 {
 				compatible = "fsl,imx6ul-uart",
 					     "fsl,imx6q-uart", "fsl,imx21-uart";