PCI: Add vendor ID for the PCI SIG

This ID is used in DOE headers to identify protocols that are defined
within the PCI Express Base Specification, PCIe r6.0, sec 6.30.1.1 table
6-32.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220719205249.566684-2-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

include/linux/pci_ids.h

@@ -151,6 +151,7 @@
 #define PCI_CLASS_OTHERS		0xff
 
 /* Vendors and devices.  Sort key: vendor first, device next. */
+#define PCI_VENDOR_ID_PCI_SIG		0x0001
 
 #define PCI_VENDOR_ID_LOONGSON		0x0014