drm/i915/cnl: Enable fifo underrun for Cannonlake.

Also in a way that reuse bdw+ for all next platforms.
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: NMika Kahola <mika.kahola@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1497047175-27250-16-git-send-email-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/intel_fifo_underrun.c

@@ -262,7 +262,7 @@ static bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
 		ironlake_set_fifo_underrun_reporting(dev, pipe, enable);
 	else if (IS_GEN7(dev_priv))
 		ivybridge_set_fifo_underrun_reporting(dev, pipe, enable, old);
-	else if (IS_GEN8(dev_priv) || IS_GEN9(dev_priv))
+	else if (INTEL_GEN(dev_priv) >= 8)
 		broadwell_set_fifo_underrun_reporting(dev, pipe, enable);
 
 	return old;