[libata] struct pci_dev related cleanups
* remove pointless pci_dev_to_dev() wrapper. Just directly reference
the embedded struct device like everyone else does.
* pata_cs5520: delete cs5520_remove_one(), it was a duplicate of
ata_pci_remove_one()
* linux/libata.h: don't bother including linux/pci.h, we don't need it.
Simply declare 'struct pci_dev' and assume interested parties will
include the header, as they should be doing anyway.
* linux/libata.h: consolidate all CONFIG_PCI declarations into a
single location in the header.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>