Following patch changes the K8M890 VGA handling. It reverts the framebuffer size

Following patch changes the K8M890 VGA handling. It reverts the framebuffer size
to option based (similar what Uwe did) and also it uses GFXUMA to handle the
high_tables_start offset from memory top.

To satisfy the CMOS option users (Hi, libv!  ;)  I added also a possibility to do
that through CMOS.

Fixed printks to match the new style.

Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5494 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1