Implement native VGA Support.

Implement native VGA Support.

This code brings a rather complete set of VGA IO routines for whoever wants it.
These consist of the by now familiar read/write/mask sets. Due to the crazy
nature of VGA, an ancient standard with bits all over the place, it makes no
sense to define individual registers. You need a vga register spec at hand if
you want to do anything anyway. These IO routines are always exposed.

It also provides code to natively set up a 640x400 VGA textmode with an 8x16
font. The native VGA mode code is behind the OPTION_VGA option, as the font
really adds to the size of the compiled/compressed rom. The font is the one
also present in the linux kernel, but this file is unlicensed. Another copy of
this is also present in coreboot in the deprecated console/btext code.

The vga console code has been cleaned up, but it still has some TODO's left
open, but that's for when i finally have found the remaining issue with the
epia-m. Right now, it is important to get parts of my work out already and to
make the remainder managable again.

Signed-off-by: Luc Verhaegen <libv@skynet.be>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@4321 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1