cuse: prevent clone

stable inclusion
from linux-4.19.191
commit 2bb2ff46d21d6794fd298df177199a2bb3b98434

--------------------------------

[ Upstream commit 8217673d ]

For cloned connections cuse_channel_release() will be called more than
once, resulting in use after free.

Prevent device cloning for CUSE, which does not make sense at this point,
and highly unlikely to be used in real life.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>