PCI/CXL: Move CXL Vendor ID to pci_ids.h

PCI/CXL: Move CXL Vendor ID to pci_ids.h

Move PCI_DVSEC_VENDOR_ID_CXL in CXL private code to PCI_VENDOR_ID_CXL in
pci_ids.h in order to be utilized in PCI subsystem.

While the CXL Vendor ID (0x1e98) is not listed in the PCI SIG "Member
Companies" database at https://pcisig.com/membership/member-companies, the
SIG has confirmed that it is reserved by CXL.

Link: https://lore.kernel.org/r/20240502165851.1948523-2-dave.jiang@intel.com
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Link: https://lore.kernel.org/linux-cxl/20240402172323.GA1818777@bhelgaas/
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
[bhelgaas: update commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>