um: virtio_uml: mark device as unregistered when breaking it

um: virtio_uml: mark device as unregistered when breaking it

[ Upstream commit 6264cc75a94511da2ae8646eebb128d6d12cd09d ]

Mark the device as not registered anymore when scheduling the work to
remove it. Otherwise we could end up scheduling the work multiple times
in a row, including scheduling it while it is already running.

Fixes: 771c89cc2180 ("um: virtio_uml: Fix broken device handling in time-travel")
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>