Drop the override conditions to ADC_MCUX_12B1MSPS_SAR for imxrt, the
current one causes the driver to be built when it does not have to and
are not needed anyway, and drop the HAS_MCUX_12B1MSPS_SAR option
entirely as it's not needed anymore.
Tested with:
west build -p -b teensy40 tests/lib/devicetree/api_ext
Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>