dt-bindings: spi: Add STM32 OSPI controller

Add device tree bindings for the STM32 OSPI controller.

Main features of the Octo-SPI controller :
  - support sNOR / sNAND / HyperRAM™ and HyperFlash™ devices.
  - Three functional modes: indirect, automatic-status polling,
    memory-mapped.
  - Up to 4 Gbytes of external memory can be addressed in indirect
    mode (per physical port and per CS), and up to 256 Mbytes in
    memory-mapped mode (combined for both physical ports and per CS).
  - Single-, dual-, quad-, and octal-SPI communication.
  - Dual-quad communication.
  - Single data rate (SDR) and double transfer rate (DTR).
  - Maximum target frequency is 133 MHz for SDR and 133 MHz for DTR.
  - Data strobe support.
  - DMA channel for indirect mode.
  - Double CS mapping that allows two external flash devices to be
    addressed with a single OCTOSPI controller mapped on a single
    OCTOSPI port.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20250219080059.367045-2-patrice.chotard@foss.st.com


Signed-off-by: Mark Brown <broonie@kernel.org>