CIFS: Fix a memory leak when a lease break comes

commit 1a05096de82f3cd672c76389f63964952678506f upstream.

This happens when we receive a lease break from a server, then
find an appropriate lease key in opened files and schedule the
oplock_break slow work. lw pointer isn't freed in this case.

Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>