[coreboot] AGESA fam15 code removals

[Stefan Reinauer]

* Martin Roth via coreboot <coreboot at coreboot.org> [171005 19:00]:
> I've got very mixed feelings about pushing the changes that we know aren't
> going to work, especially right before we abandon the boards to a branch.

We are not abandoning any boards. The whole reason we are doing branches
and not tags is that boards can be fixed on older branches after they
are no longer part of ToT.

Part of keeping coreboot flexible and fresh is to reduce the amount of
boards one has to consider for any given change. Trying to keep boards
forever was great when we had 30 boards in the tree, and Ron had all of
them. These days we add 30 boards per year or more, and 10yr old silicon
does not bring a whole lot to the table for making the latest and
greatest coreboot better. If it makes the code much worse and nobody
maintains it, it should live in a branch. Where it also does not further
decay without testing, so it really is a win win situation both for old
and new boards.

Stefan