dt-bindings: memory-controllers: Add STM32 Octo Memory Manager controller

dt-bindings: memory-controllers: Add STM32 Octo Memory Manager controller

Add bindings for STM32 Octo Memory Manager (OMM) controller.

OMM manages:
  - the muxing between 2 OSPI busses and 2 output ports.
    There are 4 possible muxing configurations:
      - direct mode (no multiplexing): OSPI1 output is on port 1 and OSPI2
        output is on port 2
      - OSPI1 and OSPI2 are multiplexed over the same output port 1
      - swapped mode (no multiplexing), OSPI1 output is on port 2,
        OSPI2 output is on port 1
      - OSPI1 and OSPI2 are multiplexed over the same output port 2
  - the split of the memory area shared between the 2 OSPI instances.
  - chip select selection override.
  - the time between 2 transactions in multiplexed mode.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250428-upstream_ospi_v6-v11-1-1548736fd9d2@foss.st.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>