Map touchscreen input device to specific display

Sometimes at Qt application startup there is not yet available real touch device and configured devices (e.g. via QT_QPA_EGLFS_KMS_CONFIG and/or QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS)point to symbolic link. When new touch device is added via udev it is the real device and does not match to any configured symbolic device names. 

Also it's not possible to know the final device name as those are added in unknown order, so mapping cannot be done at configuration time (we don't know the final device name).