dts: zynqmp: add missing destination mailbox compatible

The commit in linux kernel 81186dc16101 ("dt-bindings: zynqmp: add
destination mailbox compatible") make compatible string for child nodes
mandatory that's why add it.

Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Link: https://lore.kernel.org/r/20231204215620.63334-5-tanmay.shah@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/arch/arm/dts/zynqmp.dtsi b/arch/arm/dts/zynqmp.dtsi
index 58a56bc..21be909 100644
--- a/arch/arm/dts/zynqmp.dtsi
+++ b/arch/arm/dts/zynqmp.dtsi
@@ -148,6 +148,7 @@
 
 		ipi_mailbox_pmu1: mailbox@ff9905c0 {
 			bootph-all;
+			compatible = "xlnx,zynqmp-ipi-dest-mailbox";
 			reg = <0x0 0xff9905c0 0x0 0x20>,
 			      <0x0 0xff9905e0 0x0 0x20>,
 			      <0x0 0xff990e80 0x0 0x20>,