Hello hardworking developers,
if someone wants to test "USB Device Stack # 3890" on Phytec boards or want to use the Board (PhyNode, pba-d-01-kw2x) as a boarder router, I have completed the PR with instructions for the modifications [1].
[1] https://github.com/RIOT-OS/RIOT/pull/3890#issuecomment-154106351