ftrace, trivial: fix typo "resgister" -> "register"

Signed-off-by: Uwe Kleine-Koenig <ukleinek@strlen.de>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/trace/ftrace.c

@@ -1894,7 +1894,7 @@ int register_ftrace_function(struct ftrace_ops *ops)
 }
 
 /**
- * unregister_ftrace_function - unresgister a function for profiling.
+ * unregister_ftrace_function - unregister a function for profiling.
  * @ops - ops structure that holds the function to unregister
  *
  * Unregister a function that was added to be called by ftrace profiling.