[coreboot] [PATCH]Some more mptables updates

[Patrick Georgi]

Hi,

conversion of mptable.c to use mptable_write_buses is still ongoing.
This patch handles a set of boards that do the bus handling reasonably
similar to each other.
All of them are abuild tested, none are boot tested.

This patch touches:
amd/dbm690t
amd/mahogany
amd/mahogany_fam10
amd/pistachio
amd/tilapia_fam10
asrock/939a785gmh
asus/m4a785-m
gigabyte/ma785gmt
gigabyte/ma78gm
iei/kino-780am2-fam10
jetway/pa78vm5
kontron/kt690
technexion/tim5690
technexion/tim8690

Signed-off-by: Patrick Georgi