kconfig: add board Kconfig and defconfig files

This commit adds:
 - arch/${ARCH}/Kconfig
    provide a menu to select target boards
 - board/${VENDOR}/${BOARD}/Kconfig or board/${BOARD}/Kconfig
    set CONFIG macros to the appropriate values for each board
 - configs/${TARGET_BOARD}_defconfig
    default setting of each board

(This commit was automatically generated by a conversion script
based on boards.cfg)

In Linux Kernel, defconfig files are located under
arch/${ARCH}/configs/ directory.
It works in Linux Kernel since ARCH is always given from the
command line for cross compile.

But in U-Boot, ARCH is not given from the command line.
Which means we cannot know ARCH until the board configuration is done.
That is why all the "*_defconfig" files should be gathered into a
single directory ./configs/.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/cpu/mpc512x/Kconfig b/arch/powerpc/cpu/mpc512x/Kconfig
new file mode 100644
index 0000000..bfc4eae
--- /dev/null
+++ b/arch/powerpc/cpu/mpc512x/Kconfig
@@ -0,0 +1,34 @@
+menu "mpc512x CPU"
+	depends on MPC512X
+
+config SYS_CPU
+	string
+	default "mpc512x"
+
+choice
+	prompt "Target select"
+
+config TARGET_PDM360NG
+	bool "Support pdm360ng"
+
+config TARGET_ARIA
+	bool "Support aria"
+
+config TARGET_MECP5123
+	bool "Support mecp5123"
+
+config TARGET_MPC5121ADS
+	bool "Support mpc5121ads"
+
+config TARGET_AC14XX
+	bool "Support ac14xx"
+
+endchoice
+
+source "board/davedenx/aria/Kconfig"
+source "board/esd/mecp5123/Kconfig"
+source "board/freescale/mpc5121ads/Kconfig"
+source "board/ifm/ac14xx/Kconfig"
+source "board/pdm360ng/Kconfig"
+
+endmenu