[PATCH]fallback/normal switch for Kconfig

[Patrick Georgi]

Hi,

attached patch provides a working fallback/normal switch mechanism. It
only works with "tiny bootblock" style builds and allows for more
bootblock-level decision code to be added to the tree (eg. select based
on GPIO, CPUID, etc.), without duplicating that stuff in every single of
our mainboard directories.

It also renames the tinybootblock-related files to just "bootblock", as
this model should be the longterm goal in my opinion.

Given that I had to shuffle files around for this commit, this seemed
the right opportunity to do it.

Various Kconfig labels that refer to TINY_BOOTBLOCK still exist, but
it's not such a big impact to change these like file renames. Also there
are more things to clean up, eg. FALLBACK_PAYLOAD_FILE.

To apply the patch, src/arch/i386/init/bootblock.c must be copied to
    src/arch/i386/include/bootblock_common.h
    src/arch/i386/init/bootblock_normal.c
    src/arch/i386/init/bootblock_simple.c
and bootblock.c itself be removed (the patch does that, but your
patch(1) might not delete the file properly).

To build a full fallback/normal image, two build steps are necessary, as
done by this script:

make distclean
cp fallback-config .config
make oldconfig
make || exit
make clean-for-update
cp normal-config .config
make oldconfig
make

fallback-config and normal-config can be configured as similar or
different to each other as you want, but at a minimum, the following is
necessary:

fallback-config:
  CONFIG_CBFS_PREFIX="fallback"
  # CONFIG_UPDATE_IMAGE is not set

normal-config:
  CONFIG_CBFS_PREFIX="normal"
  CONFIG_UPDATE_IMAGE=y

Signed-off-by: Patrick Georgi