VMware: remove dsutil.split_datastore_path

The functionality of split_datatore_path has been subsumed by
the DatastorePath utility class, so remove it and convert
all callers to use the latter.

Change-Id: I07a2cfe15fccaca4aee25bc43157e6c604b91831
Merge "VMware: remove dsutil.split_datastore_path"