drm/i915: don't prevent CPU idle states

Commit 9ee32fea unconditionally prevents the CPU from entering idle states
until intel_dp_aux_ch completes for the first time, which never happens on my
DisplayPort-less intel gfx, causing the CPU to get rather hot.
Signed-off-by: Tomas Janousek <tomi@nomi.cz>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -2732,7 +2732,7 @@ void intel_irq_init(struct drm_device *dev)
 	setup_timer(&dev_priv->hangcheck_timer, i915_hangcheck_elapsed,
 		    (unsigned long) dev);
 
-	pm_qos_add_request(&dev_priv->pm_qos, PM_QOS_CPU_DMA_LATENCY, 0);
+	pm_qos_add_request(&dev_priv->pm_qos, PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);
 
 	dev->driver->get_vblank_counter = i915_get_vblank_counter;
 	dev->max_vblank_count = 0xffffff; /* only 24 bits of frame count */