Merge tag 'mediatek-for-next-2026-03-17' of https://source.denx.de/u-boot/custodians...

- A fix for mt8188 clock oscillator rates.
- New driver for mt8189 clocks.
- The rest is a first wave of a larger effort to refactor and clean up the
  mediatek clocks to replace various hacks that built up over time with
  something that is easier to understand and maintain.