USB: ratelimit debounce error messages

flaky hardware can cause a lot of debounce failed messages. To limit
the performance impact, a ratelimit should be used.

Signed-off-by: Oliver Neukum <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/hub.c

···
 
 	if (portchange & USB_PORT_STAT_C_CONNECTION) {
 		status = hub_port_debounce(hub, port1);
-		if (status < 0) {
+		if (status < 0 && printk_ratelimit()) {
 			dev_err (hub_dev,
 				"connect-debounce failed, port %d disabled\n",
 				port1);