block: remove __generic_unplug_device() from exports

The only out-of-core user is IDE, and that should be using
blk_start_queueing() instead.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk.h b/block/blk.h
index e5c5797..d2e49af 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -20,6 +20,7 @@
 void blk_rq_timed_out_timer(unsigned long data);
 void blk_delete_timer(struct request *);
 void blk_add_timer(struct request *);
+void __generic_unplug_device(struct request_queue *);
 
 /*
  * Internal atomic flags for request handling