drm/i915/skl: revert duplicated WaBarrierPerformanceFixDisable:skl
drm/i915/skl: revert duplicated WaBarrierPerformanceFixDisable:skl

With this simple git diff command one can see that skl_init_workarounds()
got two copies of WaBarrierPerformanceFixDisable:skl:

 git diff -U21 ca6e4405779e^1 ca6e4405779e drivers/gpu/drm/i915/intel_ringbuffer.c

This happened when the backmerge of drm-intel-fixes-2015-07-15
Merged the same fix on both sides. Same fix but not identical enough for
git: with a different surrounding context; hence the code duplication.

This commit merely reverts the output of the git command above
 = the duplication introduced in the backmerge.

(This duplication was found while running git sanity checks on a
_linearized_ i915 forklift for ChromeOS.)

Signed-off-by: Marc Herbert <77e7c7d746b52c6eb01119b65a031ae1f650246d@intel.com>
Reviewed-by: Rodrigo Vivi <f714145d6ee82178e54021e0c168f56d17b53c9c@intel.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs