Merge changes I09ab0a5c,I87d0a492,I613a52ae,I2fcd8d32,Ie91527a7, ... into integration

* changes:
  feat(stm32mp2): manage DDR FW via FIP
  feat(stm32mp2): introduce DDR type compilation flags
  feat(stm32mp2): add RISAB registers description
  feat(stm32mp2-fdts): add BL31 info in fw-config
  feat(stm32mp2): add minimal support for BL31
  feat(st): manage BL31 FCONF load_info struct