usb: host: xhci: use snprintf() in xhci_decode_trb()

Commit cbf286e8 ("xhci: fix unsafe memory usage in xhci tracing")
apparently missed one sprintf() call in xhci_decode_trb() -- replace
it with the snprintf() call as well...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Fixes: cbf286e8 ("xhci: fix unsafe memory usage in xhci tracing")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220630124645.1805902-2-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.h

@@ -2417,7 +2417,7 @@ static inline const char *xhci_decode_trb(char *str, size_t size,
 			field3 & TRB_CYCLE ? 'C' : 'c');
 		break;
 	case TRB_STOP_RING:
-		sprintf(str,
+		snprintf(str, size,
 			"%s: slot %d sp %d ep %d flags %c",
 			xhci_trb_type_string(type),
 			TRB_TO_SLOT_ID(field3),