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

drivers/cxl/pci.c

@@ -160,7 +160,7 @@ static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
 	writeq(cmd_reg, cxlds->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
 
 	/* #4 */
-	dev_dbg(dev, "Sending command\n");
+	dev_dbg(dev, "Sending command: 0x%04x\n", mbox_cmd->opcode);
 	writel(CXLDEV_MBOX_CTRL_DOORBELL,
 	       cxlds->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);