migration: remove register_savevm()

migration: remove register_savevm()

We can replace the four remaining calls of register_savevm() by
calls to register_savevm_live(). So we can remove the function and
as we don't allocate anymore the ops pointer with g_new0()
we don't have to free it then.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>