[libata] pata_marvell: CONFIG_AHCI is really CONFIG_SATA_AHCI

The marvell driver comtains a fallback to ahci for the sata ports
which is incorrectly checked as CONFIG_AHCI while the only AHCI config
item is actually called SATA_AHCI (which also sounds sensible
considering it's a fallback for the sata ports).

Signed-off-by: Christoph Egger <siccegge@stud.informatik.uni-erlangen.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>