haswell: Update GPU power management setup

This is the steps outlined in the BWG.

It seems this is a lot simpler now (so far) which is good.

To test, boot to chromeos with 3.7 kernel + i915.preliminary_hw_support=1 and
see that the i915 driver complains a lot less than before and that a
splashscreen is displayed.

Change-Id: I722c90ecd351860949cedab24533f6c10e5b90e5
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/2696
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
1 file changed