PCI: Replace magic constant for PCI Sig Vendor ID

PCI: Replace magic constant for PCI Sig Vendor ID

Replace the magic value in pci_bus_crs_vendor_id() with
PCI_VENDOR_ID_PCI_SIG.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20220719205249.566684-3-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>