Fix cppcheck warning "buffer may not be null-terminated after call to strncpy()"

libnfc/drivers/pn53x_usb.c

@@ -295,6 +295,7 @@ pn53x_usb_get_usb_device_name(struct usb_device *dev, usb_dev_handle *udev, char
       if ((pn53x_usb_supported_devices[n].vendor_id == dev->descriptor.idVendor) &&
           (pn53x_usb_supported_devices[n].product_id == dev->descriptor.idProduct)) {
         strncpy(buffer, pn53x_usb_supported_devices[n].name, len);
+        buffer[len - 1] = '\0';
         return true;
       }
     }