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/board/freescale/t102xrdb/Kconfig b/board/freescale/t102xrdb/Kconfig
index 10d49f5..d538386 100644
--- a/board/freescale/t102xrdb/Kconfig
+++ b/board/freescale/t102xrdb/Kconfig
@@ -1,4 +1,4 @@
-if TARGET_T102XRDB
+if TARGET_T1023RDB || TARGET_T1024RDB
 
 config SYS_BOARD
 	default "t102xrdb"