Add Supermicro X7DB8 motherboard

This adds basic supported for the Supermicro X7DB8. Basic means that
almost all onboard peripherals are working. Known problems are:

- mptable needs to be written dynamically. If you plan to use Add on
cards, modify mptable.c according to your needs. A patch to add generic
mptable autogeneration based on devicetree is coming up.

Change-Id: I5eaac32a8bafa69a05929cf08d869127b9464661
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/493
Tested-by: build bot (Jenkins)
9 files changed