ring-buffer: Fix typo in comment

Fix typo of the word 'been'

Link: http://lkml.kernel.org/r/20180518203130.2011-1-gomonovych@gmail.com

Signed-off-by: Vasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/linux/ring_buffer.h

@@ -65,7 +65,7 @@ u64 ring_buffer_event_time_stamp(struct ring_buffer_event *event);
 
 /*
  * ring_buffer_discard_commit will remove an event that has not
- *   ben committed yet. If this is used, then ring_buffer_unlock_commit
+ *   been committed yet. If this is used, then ring_buffer_unlock_commit
  *   must not be called on the discarded event. This function
  *   will try to remove the event from the ring buffer completely
  *   if another event has not been written after it.