staging: Add framebuffer driver for XGI chipsets

This driver handles XG20, XG21, XG40, XG42 chipsets from XGI. They're
also known as Z7,Z9,Z11 chipsets. It's based on the SiS fb driver but
has been heavily modified by XGI to support their newer chipsets.


Signed-off-by: Arnaud Patard <apatard@mandriva.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>