ide/macio: Fix macio DMA initialisation.

Commit 07a7484e5d713f1eb7c1c37b18a8ab0d56d88875 accidentally introduced a bug
in the initialisation of the second macio DMA device which could cause some
DMA operations to segfault QEMU.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Andreas Färber <afaerber@suse.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Alexander Graf <agraf@suse.de>