Fix bug volume cloning feature is broken
Fix bug volume cloning feature is broken

The field DataSource should be a string with full
information about the source of volume. For example,
snap://vol-name/snapshot-name

Longhorn-3508

Signed-off-by: Phan Le <2d242f367065995aaa8c677fc77edfe825ad74d9@suse.com>
(cherry picked from commit be27eeacfd094e5148e1044ba14e73cc287ee792)

rancher/longhorn