powerpc: T2080RDB: Remove macro CONFIG_T2080RDB

Use TARGET_T2080RDB from Kconfig instead.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/board/freescale/t208xrdb/Makefile b/board/freescale/t208xrdb/Makefile
index cd8fe09..25ea66a 100644
--- a/board/freescale/t208xrdb/Makefile
+++ b/board/freescale/t208xrdb/Makefile
@@ -7,7 +7,7 @@
 ifdef CONFIG_SPL_BUILD
 obj-y	+= spl.o
 else
-obj-$(CONFIG_T2080RDB) += t208xrdb.o eth_t208xrdb.o cpld.o
+obj-$(CONFIG_TARGET_T2080RDB) += t208xrdb.o eth_t208xrdb.o cpld.o
 obj-$(CONFIG_PCI)      += pci.o
 endif