i386/acpi: make floppy controller object dynamic

i386/acpi: make floppy controller object dynamic

Instead of statically declaring the floppy controller in DSDT, with its
_STA method depending on some obscure bit in the parent ISA bridge, add
the object dynamically to DSDT via AML API only when the controller is
present.

The _STA method is no longer necessary and is therefore dropped.  So are
the declarations of the fields indicating whether the contoller is
enabled.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: John Snow <jsnow@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Kevin O'Connor <kevin@koconnor.net>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>