drm/i915/skl: Disable coarse power gating up until F0

BugLink: http://bugs.launchpad.net/bugs/1527462

There is conflicting info between E0 and F0 steppings
for this workarounds. Trust more authoritative source and
be conservative and extend also for F0.

This prevents numerous (>50) gpu hangs with SKL GT4e
during piglit run.

References: HSD: gen9lp/2134184
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449505785-20812-1-git-send-email-mika.kuoppala@intel.com
(cherry picked from commit 6686ece1)
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 344df980)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -4824,7 +4824,7 @@ static void gen9_enable_rc6(struct drm_device *dev)
 	 * WaRsDisableCoarsePowerGating:skl,bxt - Render/Media PG need to be disabled with RC6.
 	 */
 	if ((IS_BROXTON(dev) && (INTEL_REVID(dev) < BXT_REVID_B0)) ||
-	    ((IS_SKL_GT3(dev) || IS_SKL_GT4(dev)) && (INTEL_REVID(dev) <= SKL_REVID_E0)))
+	    ((IS_SKL_GT3(dev) || IS_SKL_GT4(dev)) && (INTEL_REVID(dev) <= SKL_REVID_F0)))
 		I915_WRITE(GEN9_PG_ENABLE, 0);
 	else
 		I915_WRITE(GEN9_PG_ENABLE, (rc6_mask & GEN6_RC_CTL_RC6_ENABLE) ?