powerpc: T4240: Remove macro CONFIG_PPC_T4240

Use CONFIG_ARCH_T4240 from Kconfig instead.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Makefile b/arch/powerpc/cpu/mpc85xx/Makefile
index cf2aaa1..e5b45e1 100644
--- a/arch/powerpc/cpu/mpc85xx/Makefile
+++ b/arch/powerpc/cpu/mpc85xx/Makefile
@@ -44,7 +44,7 @@
 obj-$(CONFIG_ARCH_P4080) += p4080_ids.o
 obj-$(CONFIG_ARCH_P5020) += p5020_ids.o
 obj-$(CONFIG_ARCH_P5040) += p5040_ids.o
-obj-$(CONFIG_PPC_T4240) += t4240_ids.o
+obj-$(CONFIG_ARCH_T4240) += t4240_ids.o
 obj-$(CONFIG_ARCH_T4160) += t4240_ids.o
 obj-$(CONFIG_PPC_T4080) += t4240_ids.o
 obj-$(CONFIG_ARCH_B4420) += b4860_ids.o
@@ -86,7 +86,7 @@
 obj-$(CONFIG_ARCH_P4080) += p4080_serdes.o
 obj-$(CONFIG_ARCH_P5020) += p5020_serdes.o
 obj-$(CONFIG_ARCH_P5040) += p5040_serdes.o
-obj-$(CONFIG_PPC_T4240) += t4240_serdes.o
+obj-$(CONFIG_ARCH_T4240) += t4240_serdes.o
 obj-$(CONFIG_ARCH_T4160) += t4240_serdes.o
 obj-$(CONFIG_PPC_T4080) += t4240_serdes.o
 obj-$(CONFIG_ARCH_B4420) += b4860_serdes.o