Merge tag 'u-boot-stm32-20250428' of https://source.denx.de/u-boot/custodians/u-boot-stm

Merge tag 'u-boot-stm32-20250428' of https://source.denx.de/u-boot/custodians/u-boot-stm

CI: https://source.denx.de/u-boot/custodians/u-boot-stm/-/pipelines/25970
- Add OF_UPSTREAM flag support for STi, STM32 MCU and MPU platforms.
- Add ETZPC as system bus for STM32MP1 platforms
- Add RIFSC as sytem bus for STM32MP2 platforms
- Update STM32MP2 board/machine support:
  - update cmd_stm32key.
  - update cmd_stm32prog.
  - update STM32MP25 configs.
  - add leds and buttons support.
  - add boot_mode support (USB/PXE/MMC/NOR/NAND).
  - add bootcmd support.
  - enable MMC support.