piix4: Add an i8257 DMA Controller as specified in datasheet

piix4: Add an i8257 DMA Controller as specified in datasheet

The i8257 is not a chipset on the Malta board, but is part of
the PIIX4 chipset.
Create the i8257 in the PIIX4 code, remove the one instantiated
in malta board, to not have it twice.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Message-Id: <20171216090228.28505-9-hpoussin@reactos.org>
Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Esteban Bosse <estebanbosse@gmail.com>
[PMD: rebased, reworded description]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>