dt-bindings: spi: stm32: add st,stm32mp25-spi compatible

dt-bindings: spi: stm32: add st,stm32mp25-spi compatible

Add st,stm32mp25-spi compatible in dt-bindings.  STM32MP25 spi is similar
to the STM32H7 except for the following two points:
  - Burst should not be enabled with the new DMA used on STM32MP25.
  - STM32MP25 SPI8 has a limited feature set, it can only send words of
    8 or 16 bits and with a maximum words number of 1024.

Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://msgid.link/r/20231218155721.359198-3-alain.volmat@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>