Improve compatibility of YABEL with real-world VGABIOSes

Improve compatibility of YABEL with real-world VGABIOSes

Some of them do weird things to the option rom region (mapping
registers there or so) which failed as we handled these memory
region in emulation. As they were copied back to real memory
after the emulation was done, we can just as well use real
memory directly for these regions.

This affects IVT, BDA, and option ROM space.

Signed-off-by: Patrick Georgi <patrick.georgi@secunet.com>
Acked-by: Joseph Smith <joe@settoplinux.org>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6251 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1