Do not kill ioemu if undefined LSI-SCI registers are read.

Do not kill ioemu if undefined LSI-SCI registers are read.

Imported changeset from xen-unstable:

    changeset:   14902:a7bd11fd5b1b6f4a82135db09dfe654e8966fabe
    user:        kfraser@localhost.localdomain
    date:        Tue Apr 24 12:12:48 2007 +0100
    files:       tools/ioemu/hw/lsi53c895a.c
    description:
    qemu: Do not kill ioemu if undefined LSI-SCI registers are read. Just
    return zeroes. This path is triggered by ASPI8DOS.SYS in DRDOS.
    Signed-off-by: Keir Fraser <keir@xensource.com>
However, this behaviour change was inexplicably made conditional on
CONFIG_DM.  I have removed the conditionality.