Merge tag 'mmc-for-2026.07' of https://source.denx.de/u-boot/custodians/u-boot-mmc

CI: https://source.denx.de/u-boot/custodians/u-boot-mmc/-/pipelines/30621

- Fix redundant 1.8V voltage switch on cold boot with UHS card
- Revert "mmc: sdhci-cadence: trigger tuning for SD HS mode on SD6HC (v6) PHY"