ahci: Get rid of pci_dev argument in ahci_port_init()

To make the function bus-independand we have to get rid of
"struct pci_dev *", so let's pass just "struct devce *".

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>