staging: lttng: TODO update: lttng reported to work fine on -rt now

The patch "lttng: Fix recent modifications to string_from_user
operation" has been confirmed to fix the corrupted trace problem
experienced on -rt kernel by the original bug reporter. Remove the
entry from the LTTng TODO list.
Reported-by: Yannick Brosseau <yannick.brosseau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/TODO

@@ -35,12 +35,6 @@ A) Cleanup/Testing
 	   depend on the producer to push the reader position.
 	   Contact: Julien Desfossez <julien.desfossez@polymtl.ca>
 
-	4) Test latest -rt kernel support.
-	   There has been report of corrupted traces when tracing a
-	   3.0.10-rt27 in the area of access_ok() system call event.
-	   Still has to be investigated. Cannot be reproduced with
-	   mainline kernel.
-	   Contact: Yannick Brosseau <yannick.brosseau@polymtl.ca>
 
 B) Features