PCI: Reorder quirks infrastructure code

The infrastructure that applies PCI quirks was buried in the middle of the
quirks themselves (at one time it was probably at the end of the file, but
new quirks tend to be added at the end of the file).  Move it all to the
top of the file so it's easy to find.  No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>