powerpc: P1025: Remove macro CONFIG_P1025

Replace CONFIG_P1025 with ARCH_P1025 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 62c0dec..90777db 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -156,6 +156,7 @@
 	bool "Support P1025RDB"
 	select SUPPORT_SPL
 	select SUPPORT_TPL
+	select ARCH_P1025
 
 config TARGET_P2020RDB
 	bool "Support P2020RDB-PC"
@@ -164,6 +165,7 @@
 
 config TARGET_P1_TWR
 	bool "Support p1_twr"
+	select ARCH_P1025
 
 config TARGET_P2041RDB
 	bool "Support P2041RDB"
@@ -301,6 +303,9 @@
 config ARCH_P1024
 	bool
 
+config ARCH_P1025
+	bool
+
 source "board/freescale/b4860qds/Kconfig"
 source "board/freescale/bsc9131rdb/Kconfig"
 source "board/freescale/bsc9132qds/Kconfig"