Merge iopsys changes from mediatek to iop-mediatek
Original mediatek-base branch was based on u-boot 2021.10 and included unofficial mtk uplift. Merging uplifted 06.2022 u-boot there would result in lots of conflicts.
Decided to take clean upstream u-boot branch, put mediatek and iopsys changes on top of it (done in iop-mediatek-20220606).
This MR takes remaining iopsys changes from mediatek branch.