ovl: move freeing ovl_entry past rcu delay

... into ->free_inode(), that is.

Fixes: 0af950f5 "ovl: move ovl_entry into ovl_inode"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>