Merge tag 'mediatek-for-master-2026-04-17' of https://source.denx.de/u-boot/custodian...

This is the second wave of feature enablement for this merge window. We
still have a bit more waiting on review, so a 3rd wave expected to pick
those up when ready.

- Fix some wrong pinmux registers on MT7981.
- Fix a clock regression that affects MT798x.
- Add UFS support on Genio 520/720/1200.
  - Includes a number of fixes and improvements to MediaTek UFS and UFS PHY drivers.
- Add USB support on Genio 520/720.
  - Includes a new USB PHY driver for MediaTek XS-PHY.