Fix upgrade and downgrade regarding disk.dev_type

Fix upgrade and downgrade regarding disk.dev_type

The up/downgrade procedure so far did not consider the
changes in the 'dev_type' attribute of disks. This patch
adds relevant checks and updates. A related problem
was that the logical IDs of disks were adjusted depending
on the dev_type, which made the order of updates not
arbitrary anymore. To make this more robust, the upgrade
procedure also considers the old versions of dev_types
(at least for 2.9).

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>