Fix infinite loop wait for live-migration completion

PowerVC will set VM state to "Active" if the live migration failed as
the source host or dest host is running live migration. With our current
code, we are looping wait for the migration to be completed until the
powervc instance's host has been changed. That's definitely wrong..

Closes-Bug: #1393663
Change-Id: Ifb826bafa692b51f3d5997d427e10fbe17a21ca6