Now that there is a clearly defined boot state machine
we can add some useful post codes to indicate the current
point in the state machine by having it log a post code
before the execution of each state.

This removes the currently defined POST codes that were
used by hardwaremain in favor of a new contiguous range
that are defined for each boot state.

The reason for this is that the existing codes are mostly
used to indicate when something is done, which is confusing
for actual debug because POST code debugging relies on knowing
what is about to happen (to know what may be at fault) rather
than what has just finished.

One additonal change is added during device init step as this
step often does the bulk of the work, and frequently logs POST
codes itself.  Therefore in order to keep better track of what
device is being initialized POST_BS_DEV_INIT is logged before
each device is initialized.

interrupted boot with reset button and
gathered the eventlog.  Mosys has been extended to
decode the well-known POST codes:

26 | 2013-06-10 10:32:48 | System boot | 120
27 | 2013-06-10 10:32:48 | Last post code in previous boot | 0x75 | Device Initialize
28 | 2013-06-10 10:32:48 | Extra info from previous boot | PCI | 00:16.0
29 | 2013-06-10 10:32:48 | Reset Button
30 | 2013-06-10 10:32:48 | System Reset

Change-Id: Ida1e1129d274d28cbe8e49e4a01483e335a03d96
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/58106
Reviewed-on: http://review.coreboot.org/4231


Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>