xhci: show fault reason for a failed enable slot command

Show the completion code of a unsuccessful "enable slot" command.
Add it in a human readable form to the existing error message.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220921123450.671459-5-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.c

@@ -4096,7 +4096,8 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	slot_id = command->slot_id;
 
 	if (!slot_id || command->status != COMP_SUCCESS) {
-		xhci_err(xhci, "Error while assigning device slot ID\n");
+		xhci_err(xhci, "Error while assigning device slot ID: %s\n",
+			 xhci_trb_comp_code_string(command->status));
 		xhci_err(xhci, "Max number of devices this xHCI host supports is %u.\n",
 				HCS_MAX_SLOTS(
 					readl(&xhci->cap_regs->hcs_params1)));