powerpc: MPC8569: Remove macro CONFIG_MPC8569

Replace CONFIG_MPC8569 with ARCH_MPC8569 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 9545793..b58ccee 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -88,6 +88,7 @@
 
 config TARGET_MPC8569MDS
 	bool "Support MPC8569MDS"
+	select ARCH_MPC8569
 
 config TARGET_MPC8572DS
 	bool "Support MPC8572DS"
@@ -219,6 +220,9 @@
 config ARCH_MPC8568
 	bool
 
+config ARCH_MPC8569
+	bool
+
 source "board/freescale/b4860qds/Kconfig"
 source "board/freescale/bsc9131rdb/Kconfig"
 source "board/freescale/bsc9132qds/Kconfig"