vgabios: Only init BDA device details in init_bios_area()

Don't set the device details when changing modes, and don't set mode
details outside of mode setting.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
vgabios: Only set the dcc_index=8 if stdvga ports are available

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
vgabios: Move standard table definitions to std/vga.h

Move the standard video bios definitions into a new header file.
Also, define a struct with the layout for the static functionality
table.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
vgabios: Fill in available legacy modes in video_func_static at runtime

Instead of hard coding the list of modes, fill them in from the list
of supported modes.

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