Catch segfault when passing 0 to QBluetoothTransferManager::put()

Change-Id: I8c659233fd6eb2232d7bd9d904ce14f1de8a9d34
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>