drm/i915: Increase the RC6p threshold.

This increases GEN6_RC6p_THRESHOLD from 100000 to 150000. For some
reason this avoids the gen6_gt_check_fifodbg.isra warnings and
associated GPU lockups, which makes my ivy bridge machine stable.

Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -2574,7 +2574,7 @@ static void gen6_enable_rps(struct drm_device *dev)
 	I915_WRITE(GEN6_RC_SLEEP, 0);
 	I915_WRITE(GEN6_RC1e_THRESHOLD, 1000);
 	I915_WRITE(GEN6_RC6_THRESHOLD, 50000);
-	I915_WRITE(GEN6_RC6p_THRESHOLD, 100000);
+	I915_WRITE(GEN6_RC6p_THRESHOLD, 150000);
 	I915_WRITE(GEN6_RC6pp_THRESHOLD, 64000); /* unused */
 
 	/* Check if we are enabling RC6 */