drm: Kill DRM_HZ

We don't have any userspace interfaces that use HZ as a time unit, so
having our own DRM define is useless.

Remove this remnant from the shared drm core days.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/i915_dma.c

@@ -783,7 +783,7 @@ static int i915_wait_irq(struct drm_device * dev, int irq_nr)
 		master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
 
 	if (ring->irq_get(ring)) {
-		DRM_WAIT_ON(ret, ring->irq_queue, 3 * DRM_HZ,
+		DRM_WAIT_ON(ret, ring->irq_queue, 3 * HZ,
 			    READ_BREADCRUMB(dev_priv) >= irq_nr);
 		ring->irq_put(ring);
 	} else if (wait_for(READ_BREADCRUMB(dev_priv) >= irq_nr, 3000))