libata: move ata_pci_default_filter() out of CONFIG_PCI

ata_pci_default_filter() doesn't really have anything to do with PCI.
It's generally applicable to BMDMA controllers.  Move it out of
CONFIG_PCI.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>