arm64: dts: ls1046ardb: Add interrupt line for RTC node

Add interrupt line for RTC node, which is low level active.
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/fsl-ls1046a-rdb.dts

@@ -3,6 +3,7 @@
  * Device Tree Include file for Freescale Layerscape-1046A family SoC.
  *
  * Copyright 2016 Freescale Semiconductor, Inc.
+ * Copyright 2019-2020 NXP
  *
  * Mingkai Hu <mingkai.hu@nxp.com>
  */
@@ -74,6 +75,8 @@ &i2c3 {
 	rtc@51 {
 		compatible = "nxp,pcf2129";
 		reg = <0x51>;
+		/* IRQ_RTC_B -> IRQ05, active low */
+		interrupts-extended = <&extirq 5 IRQ_TYPE_LEVEL_LOW>;
 	};
 };