Can use vma->is_ggtt to simplify the check and also switch the
BUG_ON to GEM_BUG_ON which is more appropriate for this.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NDave Gordon <david.s.gordon@intel.com>