PCI: Convert device-specific ACS quirks from NULL termination to ARRAY_SIZE

Convert the search for device-specific ACS enable quirks from searching a
NULL-terminated array to iterating through the array, which is always
fixed-size anyway.  No functional change intended.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
[bhelgaas: changelog, split to separate patch for reviewability]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>