pciutils: Decode Compute eXpress Link DVSEC

pciutils: Decode Compute eXpress Link DVSEC

Compute eXpress Link[1] is a new CPU interconnect created with
workload accelerators in mind. The interconnect relies on PCIe
electrical and physical interconnect for communication via a Flex Bus
port which allows designs to choose between providing PCIe or CXL.

This patch introduces basic support for lspci decode of CXL and
builds upon the existing Designated Vendor-Specific support in
lspci through identification of a supporting CXL device using DVSEC
Vendor ID and DVSEC ID.

[1] https://www.computeexpresslink.org/

Signed-off-by: Sean V Kelley <sean.v.kelley@linux.intel.com>