Merge changes from topic "st_regulator" into integration

Merge changes from topic "st_regulator" into integration

* changes:
  feat(st-sdmmc2): manage cards power cycle
  feat(stm32mp1): register fixed regulator
  feat(st-drivers): introduce fixed regulator driver
  refactor(st): update CPU and VDD voltage get
  refactor(stm32mp1-fdts): update regulator description
  refactor(st-pmic): use regulator framework for DDR init
  feat(st-pmic): register the PMIC to regulator framework
  refactor(st-pmic): split initialize_pmic()
  feat(stm32mp1): add regulator framework compilation
  feat(regulator): add a regulator framework
  feat(stpmic1): add new services
  feat(stpmic1): add USB OTG regulators
  refactor(st-pmic): improve driver usage
  refactor(stpmic1): set stpmic1_is_regulator_enabled() as boolean
  refactor(stm32mp1): re-order drivers init