soc: mt8195: remove prompts for SoC kconfigs

This removes the prompts for the mt8195 and related kconfigs,
so these cannot be overridden from command line (though
technically they cannot be disabled as they are being selected).
This also prevents them from appearing in the build .config
file as not being set even when we are being for other SoCs.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>