libata: dev_config does not need ap and adev passing

It used to be impossible to get from ata_device to ata_port but that is
no longer true. Various methods have been cleaned up over time but
dev_config still takes both and most users don't need both anyway. Tidy
this one up

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>