usb: dwc3: trace: add missing break statement to make compiler happy

The missed break statement in the outer switch makes the code fall through
always and thus always same value will be printed.

Besides that, compiler warns about missed fall through marker:

drivers/usb/dwc3/./trace.h: In function ‘trace_raw_output_dwc3_log_trb’:
drivers/usb/dwc3/./trace.h:246:4: warning: this statement may fall through [-Wimplicit-fallthrough=]
    switch (pcm) {
    ^~~~~~

Add the missing break statement to work correctly without compilation
warnings.

Fixes: fa8d965d73 ("usb: dwc3: trace: pretty print high-bandwidth transfers too")
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/trace.h

@@ -251,9 +251,11 @@ DECLARE_EVENT_CLASS(dwc3_log_trb,
 				s = "2x ";
 				break;
 			case 3:
+			default:
 				s = "3x ";
 				break;
 			}
+			break;
 		default:
 			s = "";
 		} s; }),