QtIFW

Fix could not write installer configuration file.

Task-number: QTIFW-621
Change-Id: Iad160efc3c9123476d0fd0d676a0ce751025778a
Reviewed-by: Niels Weber <niels.weber@theqtcompany.com>
Reviewed-by: Christoph Vogtländer <c.vogtlaender@sigma-surface-science.com>
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>