mpc83xx: Introduce ARCH_MPC836*

Replace CONFIG_MPC836* with proper CONFIG_ARCH_MPC836* Kconfig options.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/arch/powerpc/cpu/mpc83xx/Kconfig b/arch/powerpc/cpu/mpc83xx/Kconfig
index 6cca45e..5f9d036 100644
--- a/arch/powerpc/cpu/mpc83xx/Kconfig
+++ b/arch/powerpc/cpu/mpc83xx/Kconfig
@@ -80,6 +80,7 @@
 
 config TARGET_KM8360
 	bool "Support km8360"
+	select ARCH_MPC8360
 	imply CMD_CRAMFS
 	imply CMD_DIAG
 	imply FS_CRAMFS
@@ -147,6 +148,9 @@
 	bool
 	select ARCH_MPC834X
 
+config ARCH_MPC8360
+	bool
+
 source "board/esd/vme8349/Kconfig"
 source "board/freescale/mpc8308rdb/Kconfig"
 source "board/freescale/mpc8313erdb/Kconfig"