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

Signed-off-by: NUwe Kleine-Koenig <ukleinek@strlen.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

kernel/trace/ftrace.c

@@ -1908,7 +1908,7 @@ 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.