ceph: avoid a use-after-free in ceph_destroy_options()

syzbot reported a use-after-free in ceph_destroy_options(), called from
ceph_mount().  The problem was that create_fs_client() consumed the opt
pointer on some errors, but not on all of them.  Make sure it always
consumes both libceph and ceph options.

Reported-by:  <syzbot+8ab6f1042021b4eed062@syzkaller.appspotmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>