pc: make isapc and pc-0.10 to pc-0.13 have 1.7.0 memory layout

QEMU 2.0 changed memory layout for isapc and pc-0.10 to pc-0.13.
This prevents migration from QEMU 1.7.0 for these
machine types when -m 3.5G is specified.

Paolo Bonzini asked that:

    smbios_legacy_mode = true;
    has_reserved_memory = false;
    option_rom_has_mr = true;
    rom_file_has_mr = false;

also be done.

Cc: qemu-stable@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Don Slutz <dslutz@verizon.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: https://bugs.launchpad.net/qemu/+bug/1334307
Tested-by: "Slutz, Donald Christopher" <dslutz@verizon.com>
