Allow YABEL to fake write accesses to config space

A new Kconfig option tells YABEL to succeed on write accesses
on other devices' config space without performing the actual
write.
This is enough for some basic bus modification done by some
Option ROMs.

Change-Id: Iab04f3a5c350b96654da4ba26858037f4c4b5c0a
Signed-off-by: Patrick Georgi <patrick.georgi@secunet.com>
Reviewed-on: http://review.coreboot.org/1249
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2 files changed