Implement ao_ioctl in stm32_comp_m3m4_v2.c to handle ANIOC_COMP_ENABLE and
ANIOC_COMP_DISABLE commands. Also add CONFIG_STM32_COMP_INIT_DISABLED to
allow keeping the comparator disabled after driver initialization until
explicitly enabled.
Update nucleo-g431kb:comp defconfig to enable CONFIG_EXAMPLES_COMP and
set default DAC path for comparator ramp verification.
Assisted-by: Gemini:gemini-2.5-pro
Signed-off-by: Daniel P. Carvalho <danieloak@gmail.com>
e433409fcc