spi: stm32: disable spi-slave property for stm32f4-f7

STM32F4 and STM32F7 can't switch to spi device mode.
Forbid this property with compatible "st,stm32f4-spi".

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230615075815.310261-4-valentin.caron@foss.st.com


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