powerpc: P5020: Remove macro CONFIG_PPC_P5020

Replace CONFIG_PPC_P5020 with ARCH_P5020 in Kconfig and clean up
existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Kconfig b/arch/powerpc/cpu/mpc85xx/Kconfig
index a68a651..808144e 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -51,6 +51,7 @@
 config TARGET_P5020DS
 	bool "Support P5020DS"
 	select PHYS_64BIT
+	select ARCH_P5020
 
 config TARGET_P5040DS
 	bool "Support P5040DS"
@@ -324,6 +325,9 @@
 config ARCH_P4080
 	bool
 
+config ARCH_P5020
+	bool
+
 source "board/freescale/b4860qds/Kconfig"
 source "board/freescale/bsc9131rdb/Kconfig"
 source "board/freescale/bsc9132qds/Kconfig"
diff --git a/arch/powerpc/cpu/mpc85xx/Makefile b/arch/powerpc/cpu/mpc85xx/Makefile
index 0ea5547..edd365a 100644
--- a/arch/powerpc/cpu/mpc85xx/Makefile
+++ b/arch/powerpc/cpu/mpc85xx/Makefile
@@ -42,7 +42,7 @@
 obj-$(CONFIG_ARCH_P2041) += p2041_ids.o
 obj-$(CONFIG_ARCH_P3041) += p3041_ids.o
 obj-$(CONFIG_ARCH_P4080) += p4080_ids.o
-obj-$(CONFIG_PPC_P5020) += p5020_ids.o
+obj-$(CONFIG_ARCH_P5020) += p5020_ids.o
 obj-$(CONFIG_PPC_P5040) += p5040_ids.o
 obj-$(CONFIG_PPC_T4240) += t4240_ids.o
 obj-$(CONFIG_PPC_T4160) += t4240_ids.o
@@ -84,7 +84,7 @@
 obj-$(CONFIG_ARCH_P2041) += p2041_serdes.o
 obj-$(CONFIG_ARCH_P3041) += p3041_serdes.o
 obj-$(CONFIG_ARCH_P4080) += p4080_serdes.o
-obj-$(CONFIG_PPC_P5020) += p5020_serdes.o
+obj-$(CONFIG_ARCH_P5020) += p5020_serdes.o
 obj-$(CONFIG_PPC_P5040) += p5040_serdes.o
 obj-$(CONFIG_PPC_T4240) += t4240_serdes.o
 obj-$(CONFIG_PPC_T4160) += t4240_serdes.o