devicemapper: fix suspend removed device
when doing devices.cancelDeferredRemoval, the device could have been removed
and return ErrEnxio, but it continue to check if it is need to do suspend.
doSuspend := devinfo != nil && devinfo.Exists != 0 uses a devinfo which is
get before devices.cancelDeferredRemoval(baseInfo), it is outdate, the device
has been removed and there is no need to do suspend. If do suspend it will return
devicemapper: Error running deviceSuspend dm_task_run failed.
Signed-off-by: Lei Jitang <leijitang@huawei.com>