Exposing POST codes

[Patrick Venture]

I talked to Nancy and I think it's time to revisit previous conversations
about POST codes.  We have a simple daemon that exposes the information
over Dbus associated with https://gerrit.openbmc-project.xyz/#/c/5006

If there's interest, I can stage it against skeleton for review and comment.

We have a patch to the kernel character device for the aspeed-lpc-snoop
that is required and enables reading the post codes.

Patrick