mainboard/lenovo/t400: Add initial hybrid graphics support

TEST: Booted T400 with Intel/ATI hybrid graphics in integrated
mode with native Intel graphics init and verified integrated
panel framebuffer functionality in SeaBIOS and Linux.

Change-Id: I37e72c5dad0d7ab3915cc3d439ae9a4a9b3787e3
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: http://review.coreboot.org/9319
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
3 files changed