dynamic_debug: fix comment

Signed-off-by: NMasatake YAMATO <yamato@redhat.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

lib/dynamic_debug.c

@@ -641,7 +641,7 @@ static __init int ddebug_setup_query(char *str)
 __setup("ddebug_query=", ddebug_setup_query);
 
 /*
- * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
+ * File_ops->write method for <debugfs>/dynamic_debug/control.  Gathers the
  * command text from userspace, parses and executes it.
  */
 #define USER_BUF_PAGE 4096