initialize MachineState::ram in NUMA case

In case of NUMA there are 2 cases to consider:
 1. '-numa node,memdev', the only one that will be available
    for 5.0 and newer machine types.

    In this case reuse current behavior, with only difference
    memdevs are put into MachineState::ram container +
    a temporary glue to keep memory_region_allocate_system_memory()
    working until all boards converted.

 2. fake NUMA ("-numa node mem" and default RAM splitting)
    the later has been deprecated and will be removed but the former
    is going to stay available for compat reasons for 5.0 and
    older machine types

    it takes allocate_system_memory_nonnuma() path, like non-NUMA
    case and falls under conversion to memdev.  So extend non-NUMA
    MachineState::ram initialization introduced in previous patch
    to take care of fake NUMA case.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200219160953.13771-6-imammedo@redhat.com>