Fixes wrong logic for clean method in SetInstanceDetailsAction

If the 'Instance Boot Source' is 'Boot from image (creates a new
volume)', the 'Device Size' and 'Device Name' fields will never be
checked.

Change-Id: Ic34de83a46716f6489d017275f9b64ce0c951858
Fixes-bug: 1313473
Merge "Fixes wrong logic for clean method in SetInstanceDetailsAction"