Add STM32MP25 SPI NOR support

Merge series from patrice.chotard@foss.st.com:

This series adds SPI NOR support for STM32MP25 SoCs from STMicroelectronics.

On STM32MP25 SoCs family, an Octo Memory Manager block manages the muxing,
the memory area split, the chip select override and the time constraint
between its 2 Octo SPI children.

Due to these depedencies, this series adds support for:
  - Octo Memory Manager driver (not applied for SPI).
  - Octo SPI driver.
  - yaml schema for Octo Memory Manager and Octo SPI drivers.

The device tree files adds Octo Memory Manager and its 2 associated Octo
SPI chidren in stm32mp251.dtsi and adds SPI NOR support in stm32mp257f-ev1
board.

diff --cc MAINTAINERS
Simple merge

diff --cc drivers/spi/Kconfig
Simple merge

diff --cc drivers/spi/Makefile
Simple merge