arm64: dts: juno: Add missing MHU secure-irq

The MHU secure interrupt exists physically but is missing in the DT node.

Specify the interrupt in DT node to fix a warning on Arm Juno board:
   mhu@2b1f0000: interrupts: [[0, 36, 4], [0, 35, 4]] is too short

Link: https://lore.kernel.org/r/20220801141005.599258-1-jassisinghbrar@gmail.comSigned-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

arch/arm64/boot/dts/arm/juno-base.dtsi

@@ -26,7 +26,8 @@ mailbox: mhu@2b1f0000 {
 		compatible = "arm,mhu", "arm,primecell";
 		reg = <0x0 0x2b1f0000 0x0 0x1000>;
 		interrupts = <GIC_SPI 36 IRQ_TYPE_LEVEL_HIGH>,
-			     <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>;
+			     <GIC_SPI 35 IRQ_TYPE_LEVEL_HIGH>,
+			     <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
 		#mbox-cells = <1>;
 		clocks = <&soc_refclk100mhz>;
 		clock-names = "apb_pclk";