ovl: fix a typo in comment

Fix a typo in comment. (annonate -> annotate)
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -504,7 +504,7 @@ static const struct address_space_operations ovl_aops = {
 
 /*
  * It is possible to stack overlayfs instance on top of another
- * overlayfs instance as lower layer. We need to annonate the
+ * overlayfs instance as lower layer. We need to annotate the
  * stackable i_mutex locks according to stack level of the super
  * block instance. An overlayfs instance can never be in stack
  * depth 0 (there is always a real fs below it).  An overlayfs