VMware: ensure that the task completed for resize operation

In the event of a VM resize, the code did not wait for the task
to complete. This may lead to a race condition.

Change-Id: I0ce28e9d83da2f0e5741ae99bfba4b0f1d20c699
Closes-bug: #1270573
Merge "VMware: ensure that the task completed for resize operation"