vhost: Fix kthread worker cgroup failure handling

vhost: Fix kthread worker cgroup failure handling

[ Upstream commit f3f64c2eaffbc3169bbe1e5d1e897e6dacc839d1 ]

If we fail to attach to a cgroup we are leaking the id. This adds
a new goto to free the id.

Fixes: 7d9896e9f6d0 ("vhost: Reintroduce kthread API and add mode selection")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20251101194358.13605-1-michael.christie@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>