Copy the Kconfig option from "init/Kconfig" of Linux v3.16 tag
and adjust the help document.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Copy Kconfig options from "init/Kconfig" of Linux v3.16 tag
and adjust some parts of the help document.

Move CONFIG_SPL, CONFIG_TPL, ... etc. to "Boot images" menu.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

CONFIG_DEFCONFIG_LIST specifies the default defconfig.
It is used by "make savedefconfig" when .config is missing.
But that's it.  I could not find other useful cases.

As a side effect, CONFIG_DEFCONFIG_LIST="configs/sandbox_defconfig"
is contained in .config of every target board, which some people
think is odd.  So, let's remove it.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>

This commit adds more Kconfig files, which were written by hand.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>