smb3: fix Open files on server counter going negative

commit 28e09476 upstream.

We were decrementing the count of open files on server twice
for the case where we were closing cached directories.

Fixes: 8e843bf3 ("cifs: return a single-use cfid if we did not get a lease")
Cc: stable@vger.kernel.org
Acked-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>