powerpc: BSC9131/2: Move CONFIG_BSC9131/2 to Kconfig options

Replace CONFIG_BSC9131, CONFIG_BSC9132 with ARCH_BSC9131, ARCH_BSC9132
Kconfig options.

Also drop #ifdef in BSC9131RDB.h since it is redundant.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Makefile b/arch/powerpc/cpu/mpc85xx/Makefile
index 744c781..e545112 100644
--- a/arch/powerpc/cpu/mpc85xx/Makefile
+++ b/arch/powerpc/cpu/mpc85xx/Makefile
@@ -96,7 +96,7 @@
 obj-$(CONFIG_PPC_T4080) += t4240_serdes.o
 obj-$(CONFIG_PPC_B4420) += b4860_serdes.o
 obj-$(CONFIG_PPC_B4860) += b4860_serdes.o
-obj-$(CONFIG_BSC9132) += bsc9132_serdes.o
+obj-$(CONFIG_ARCH_BSC9132) += bsc9132_serdes.o
 obj-$(CONFIG_PPC_T1040) += t1040_serdes.o
 obj-$(CONFIG_PPC_T1042)	+= t1040_serdes.o
 obj-$(CONFIG_PPC_T1020)	+= t1040_serdes.o