drm/i915: WARN if we receive any gen9 rps interrupts

Paulo noticed that we don't support RPS on GEN9 yet, so WARN for and
ignore any RPS interrupts on that platform.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -1690,6 +1690,11 @@ static void i9xx_pipe_crc_irq_handler(struct drm_device *dev, enum pipe pipe)
  * the work queue. */
 static void gen6_rps_irq_handler(struct drm_i915_private *dev_priv, u32 pm_iir)
 {
+	/* TODO: RPS on GEN9 is not supported yet. */
+	if (WARN_ONCE(INTEL_INFO(dev_priv)->gen == 9,
+		      "GEN9: unexpected RPS IRQ\n"))
+		return;
+
 	if (pm_iir & dev_priv->pm_rps_events) {
 		spin_lock(&dev_priv->irq_lock);
 		dev_priv->rps.pm_iir |= pm_iir & dev_priv->pm_rps_events;