core: Fix Quota accounting for move disk

When moving a disk without changing a quota the quota check is not
performed. This is a problem since the quota can be specific for each
storage domain. The logic was changed to support quota change even if
quota id was not changed.

Change-Id: I33a6a409388622bb0ab14644445a187357ce5fa2
Bug-Url: https://bugzilla.redhat.com/906499
Signed-off-by: Ofri Masad <omasad@redhat.com>