nb/intel/sandybridge/gma: add disable function

Issue observed:
In a multi GPU setup (IGD and PEG) the system still uses the IGD.
CONFIG_ONBOARD_VGA_IS_PRIMARY has no effect on Sandy/Ivy Bridge.

Test system:
* Gigabyte GA-B75M-D3H
* Intel Pentium CPU G2130
* ATI Radeon HD4780

Problem description:
The GMA is missing a disable function.

Problem solution:
Add a GMA disable function. Deactivate PCI device until remaining multi
GPU issues are resolved. Do not claim VGA decode any more.

Final testing results:
The system is able to boot using the PEG device as primary VGA
device.

Change-Id: I52af32df41ca22f808b119f3a4099849c74068b3
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: http://review.coreboot.org/11919
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions