drm/i915/skl: Updated the gen6_set_rps function

On SKL, the frequency is programmed differently in RPNSWREQ (A008)
register (from bits 23 to 31, compared to bits 24 to 31). So updated
the gen6_set_rps function, as per this change.

Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -3947,7 +3947,10 @@ static void gen6_set_rps(struct drm_device *dev, u8 val)
 	if (val != dev_priv->rps.cur_freq) {
 		gen6_set_rps_thresholds(dev_priv, val);
 
-		if (IS_HASWELL(dev) || IS_BROADWELL(dev))
+		if (IS_GEN9(dev))
+			I915_WRITE(GEN6_RPNSWREQ,
+				   GEN9_FREQUENCY(val));
+		else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
 			I915_WRITE(GEN6_RPNSWREQ,
 				   HSW_FREQUENCY(val));
 		else