drm/i915/cnl: Reuse skl_wm_get_hw_state on Cannonlake.

Otherwise it reuses the ilk that has a completely different
wm.

Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170809205248.11917-6-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -15120,7 +15120,7 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	} else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
 		vlv_wm_get_hw_state(dev);
 		vlv_wm_sanitize(dev_priv);
-	} else if (IS_GEN9(dev_priv)) {
+	} else if (INTEL_GEN(dev_priv) >= 9) {
 		skl_wm_get_hw_state(dev);
 	} else if (HAS_PCH_SPLIT(dev_priv)) {
 		ilk_wm_get_hw_state(dev);