Fix tools/move-instance after networks addition

Commits d4117a72 (“Modify LUInstanceCreate to support networks”) and
09a3d21f (“Pass detailed network info in hooks“) expanded the nic
information as computed by _NICToTuple, which means that the format of
the result value from LUInstanceQueryData has changed, and
move-instance has not been changed to deal with this.

A proper fix needs to support correctly importing from old clusters,
right now this is a temporary fix to ensure QA still passes.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>