migrate_init: Call from savevm

migrate_init: Call from savevm

Suspend to file is very much like a migrate, and it makes life
easier if we have the Migration state available, so initialise it
in the savevm.c code for suspending.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewd-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>