cxl/pci: Show opcode in debug messages when sending a command

For debugging it is very helpful to see which commands are sent. Add
it to the debug message.

Signed-off-by: Robert Richter <rrichter@amd.com>
Link: https://lore.kernel.org/r/20230103210151.1126873-1-rrichter@amd.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>