m68k: mcf523x: move CPU type to Kconfig and refactor config.mk

Move the CPU type config options from include/configs/M5235EVB.h
to arch/m68k/Kconfig and refactor the CPU flags select in
arch/m68k/cpu/mcf523x/config.mk.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Alison Wang <alison.wang@freescale.com>
Cc: Angelo Dureghello <angelo@sysam.it>
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index a645d95..a3f0cbc 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -11,6 +11,9 @@
 config MCF52x2
 	bool
 
+config MCF523x
+	bool
+
 config MCF530x
 	bool
 
@@ -37,6 +40,10 @@
 	bool
 	select MCF520x
 
+config M5235
+	bool
+	select MCF523x
+
 config M5249
 	bool
 	select MCF52x2
@@ -103,6 +110,7 @@
 
 config TARGET_M5235EVB
 	bool "Support M5235EVB"
+	select M5235
 
 config TARGET_COBRA5272
 	bool "Support cobra5272"