drm: kill dev->buf_readers and dev->buf_writers

Again totally unused, so just remove them.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/drm_fops.c

@@ -81,8 +81,6 @@ static int drm_setup(struct drm_device * dev)
 	dev->if_version = 0;
 
 	dev->buf_async = NULL;
-	init_waitqueue_head(&dev->buf_readers);
-	init_waitqueue_head(&dev->buf_writers);
 
 	DRM_DEBUG("\n");
 

include/drm/drmP.h

@@ -1172,8 +1172,6 @@ struct drm_device {
 	/*@} */
 
 	struct fasync_struct *buf_async;/**< Processes waiting for SIGIO */
-	wait_queue_head_t buf_readers;	/**< Processes waiting to read */
-	wait_queue_head_t buf_writers;	/**< Processes waiting to ctx switch */
 
 	struct drm_agp_head *agp;	/**< AGP data */