USB: cp210x: do not map baud rates to B0

We do not implement B0 hangup yet so map low baudrates to 300bps.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Cc: Preston Fick <preston.fick@silabs.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/cp210x.c

@@ -363,8 +363,8 @@ static inline int cp210x_set_config_single(struct usb_serial_port *port,
  * Quantises the baud rate as per AN205 Table 1
  */
 static unsigned int cp210x_quantise_baudrate(unsigned int baud) {
-	if      (baud <= 56)       baud = 0;
-	else if (baud <= 300)      baud = 300;
+	if (baud <= 300)
+		baud = 300;
 	else if (baud <= 600)      baud = 600;
 	else if (baud <= 1200)     baud = 1200;
 	else if (baud <= 1800)     baud = 1800;