spi: spidev: drop the incorrect notice from Kconfig

The spidev interface has been de-facto stable for many years. This notice
has been unchanged since 2007 and is incorrect so remove it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20230216123014.110541-1-brgl@bgdev.pl


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