USB: cp210x: remove useless set memory to zero use memset()

The memory return by kzalloc() or kmem_cache_zalloc() has already
be set to zero, so remove useless memset(0).

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/cp210x.c

@@ -865,7 +865,6 @@ static int cp210x_startup(struct usb_serial *serial)
 		if (!port_priv)
 			return -ENOMEM;
 
-		memset(port_priv, 0x00, sizeof(*port_priv));
 		port_priv->bInterfaceNumber =
 		    serial->interface->cur_altsetting->desc.bInterfaceNumber;