ata: use module_pci_driver

This patch converts the drivers in drivers/ata/* to use module_pci_driver()
macro which makes the code smaller and a bit simpler.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Mark Lord <kernel@teksavvy.com>
Cc: Jeremy Higdon <jeremy@sgi.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>