A number of changes to get save-restore working again:

A number of changes to get save-restore working again:

Fix the use of configuration inside domain_configure.  The config written by
XendDomainInfo.sxpr has moved, and this function needs to change to match.

Re-add a call to _add_domain inside domain_restore.

Inside XendDomainInfo.restore, perform the appropriate configuration to restore
the domain.

Validate maxmem_KiB, and cap it at memory_KiB if over that value.  Save
requires that value to be correct, as the logic for saving only the pages
in use is not in place inside Xen.

Output the device configuration in sxpr(), as required for save-restore.

Check for image being null when trying to call createDeviceModel -- configure
is called on restore as well as create, and the ImageHandler instance is not
present in the former.

Remove dead code create_blkif.

Signed-off-by: Ewan Mellor <ewan@xensource.com>