USB: serial: kobil_sct: add missing version error handling

Add missing version-request error handling and suppress printing of the
(zeroed) transfer-buffer content in case of errors.
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/kobil_sct.c

@@ -190,8 +190,10 @@ static int kobil_open(struct tty_struct *tty, struct usb_serial_port *port)
 			  KOBIL_TIMEOUT
 	);
 	dev_dbg(dev, "%s - Send get_HW_version URB returns: %i\n", __func__, result);
-	dev_dbg(dev, "Hardware version: %i.%i.%i\n", transfer_buffer[0],
-		transfer_buffer[1], transfer_buffer[2]);
+	if (result >= 3) {
+		dev_dbg(dev, "Hardware version: %i.%i.%i\n", transfer_buffer[0],
+				transfer_buffer[1], transfer_buffer[2]);
+	}
 
 	/* get firmware version */
 	result = usb_control_msg(port->serial->dev,
@@ -205,8 +207,10 @@ static int kobil_open(struct tty_struct *tty, struct usb_serial_port *port)
 			  KOBIL_TIMEOUT
 	);
 	dev_dbg(dev, "%s - Send get_FW_version URB returns: %i\n", __func__, result);
-	dev_dbg(dev, "Firmware version: %i.%i.%i\n", transfer_buffer[0],
-		transfer_buffer[1], transfer_buffer[2]);
+	if (result >= 3) {
+		dev_dbg(dev, "Firmware version: %i.%i.%i\n", transfer_buffer[0],
+				transfer_buffer[1], transfer_buffer[2]);
+	}
 
 	if (priv->device_type == KOBIL_ADAPTER_B_PRODUCT_ID ||
 			priv->device_type == KOBIL_ADAPTER_K_PRODUCT_ID) {