cifs: remove bogus call to cifs_cleanup_volume_info

This call to cifs_cleanup_volume_info is clearly wrong. As soon as it's
called the following call to cifs_get_tcp_session will oops as the
volume_info pointer will then be NULL.

The caller of cifs_mount should clean up this data since it passed it
in. There's no need for us to call this here.

Regression introduced by commit 724d9f1c.

Reported-by: Adam Williamson <awilliam@redhat.com>
Cc: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>