swarm: use struct ide_port_info

Convert the driver to use struct ide_port_info.

There should be no functional changes caused by this patch.

Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Tested-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>