Previously, we allow multiple nodes can resync device, but we
had changed it to only support one node can do resync at one
time, but suspend_info is still used.

Now, let's remove the structure and use suspend_lo/hi to record
the range.
Reviewed-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NGuoqing Jiang <gqjiang@suse.com>
Signed-off-by: NShaohua Li <shli@fb.com>