arm64: zynqmp: Add label for zynqmp_ipi

Add label which is used by bootloader for adding bootloader specific flag.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/3dc8416abdd3498e61edcd83830a12af295c5c6d.1611224800.git.michal.simek@xilinx.com
diff --git a/arch/arm/dts/zynqmp.dtsi b/arch/arm/dts/zynqmp.dtsi
index 345ab97..deb3fa3 100644
--- a/arch/arm/dts/zynqmp.dtsi
+++ b/arch/arm/dts/zynqmp.dtsi
@@ -100,7 +100,7 @@
 		};
 	};
 
-	zynqmp_ipi {
+	zynqmp_ipi: zynqmp_ipi {
 		u-boot,dm-pre-reloc;
 		compatible = "xlnx,zynqmp-ipi-mailbox";
 		interrupt-parent = <&gic>;