Change in coreboot[master]: drvs/intel/gma/acpi: Add methods to use MBOX3

[Patrick Rudolph (Code Review)]

Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/27711

to look at the new patch set (#2).

Change subject: drvs/intel/gma/acpi: Add methods to use MBOX3
......................................................................

drvs/intel/gma/acpi: Add methods to use MBOX3

* Add Mailbox 3 driver
* Request brightness change through Mailbox 3
* Return Ones on error or if unsupported
* Mark existing code as legacy
  (still required if no GMA driver is running)
* Call legacy code if Mailbox 3 is unsupported, on error or
  if gma driver isn't running

Tested on Lenovo T430:
* Brightness control still works
* Brightness is the same on S3 resume

Change-Id: I51554c819148336b204d28972cbf775a10c3fb8a
Signed-off-by: Patrick Rudolph 
---
M src/drivers/intel/gma/acpi/common.asl
M src/drivers/intel/gma/acpi/configure_brightness_levels.asl
M src/drivers/intel/gma/acpi/non-pch.asl
M src/drivers/intel/gma/acpi/pch.asl
4 files changed, 152 insertions(+), 21 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/11/27711/2