xhci: Remove scary warnings about transfer issues.

Getting a short packet or a babble error is usually a recoverable error,
so stop scaring users with warnings in dmesg when xHCI debugging is turned
off.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci-ring.c

@@ -1643,7 +1643,6 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
 		}
 		break;
 	case COMP_SHORT_TX:
-		xhci_warn(xhci, "WARN: short transfer on control ep\n");
 		if (td->urb->transfer_flags & URB_SHORT_NOT_OK)
 			*status = -EREMOTEIO;
 		else
@@ -1985,7 +1984,7 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 		xhci_dbg(xhci, "Stopped on No-op or Link TRB\n");
 		break;
 	case COMP_STALL:
-		xhci_warn(xhci, "WARN: Stalled endpoint\n");
+		xhci_dbg(xhci, "Stalled endpoint\n");
 		ep->ep_state |= EP_HALTED;
 		status = -EPIPE;
 		break;
@@ -1995,11 +1994,11 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 		break;
 	case COMP_SPLIT_ERR:
 	case COMP_TX_ERR:
-		xhci_warn(xhci, "WARN: transfer error on endpoint\n");
+		xhci_dbg(xhci, "Transfer error on endpoint\n");
 		status = -EPROTO;
 		break;
 	case COMP_BABBLE:
-		xhci_warn(xhci, "WARN: babble error on endpoint\n");
+		xhci_dbg(xhci, "Babble error on endpoint\n");
 		status = -EOVERFLOW;
 		break;
 	case COMP_DB_ERR: