powerpc: dts: t4240rdb: add serial nodes

Add the serial node descriptions similar to Linux v6.4 for the t4240rdb
board and its dependencies.

Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/powerpc/dts/t4240rdb.dts b/arch/powerpc/dts/t4240rdb.dts
index b3251e3..c33b498 100644
--- a/arch/powerpc/dts/t4240rdb.dts
+++ b/arch/powerpc/dts/t4240rdb.dts
@@ -3,7 +3,7 @@
  * T4240RDB Device Tree Source
  *
  * Copyright 2013 - 2015 Freescale Semiconductor Inc.
- * Copyright 2019-2021 NXP
+ * Copyright 2019-2023 NXP
  */
 
 /include/ "t4240.dtsi"
@@ -17,6 +17,10 @@
 
 	aliases {
 		spi0 = &espi0;
+		serial0 = &serial0;
+		serial1 = &serial1;
+		serial2 = &serial2;
+		serial3 = &serial3;
 	};
 };