coreboot: Add support for a "links" file to have aliases in CBFS.

The "links" file is a newline separated list where each line is a
"link name" followed by a "destination name" separated by a space
character.  For each line, SeaBIOS will consider each "link name" to
be a CBFS file that has the contents found in the CBFS file with
"destination name".

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Enhance nullTrailingSpace() so that it can also skip leading spaces.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
coreboot: Move links file processing to its own function.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
vgabios: Add support for native coreboot EGA style text consoles.

If a CB_TAG_FRAMEBUFFER coreboot table isn't found, assume there is a
standard text mode console mapped at 0xB8000.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>