powerpc: T102xRDB: Split as T1023RDB and T1024RDB

The defconfig files are separated. Splitting targets in Kconfig simplifies
config options.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Kconfig b/arch/powerpc/cpu/mpc85xx/Kconfig
index 11ae4ea..8b857d5 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -194,8 +194,13 @@
 	select SUPPORT_SPL
 	select PHYS_64BIT
 
-config TARGET_T102XRDB
-	bool "Support T102xRDB"
+config TARGET_T1023RDB
+	bool "Support T1023RDB"
+	select SUPPORT_SPL
+	select PHYS_64BIT
+
+config TARGET_T1024RDB
+	bool "Support T1024RDB"
 	select SUPPORT_SPL
 	select PHYS_64BIT