pata_ixp4xx_cf: fix compilation introduced by ata_port_desc() conversion

Fixes a compilation error caused by ata_port_desc() conversion
(cbcdd875).

Signed-off-by: Rod Whitby <rod@whitby.id.au>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>