sensor: mcp9600: extend driver functionality

Add support for runtime and devicetree configuration of themocouple
type, ADC resolution, filter coefficient and cold junction temperature
resolution. Extend device specific sensor channels to include cold
junction temperature, delta tempereature, hot junction temperature and
raw ADC values while still maintaining backwards compability with the
existing SENSOR_CHAN_AMBIENT_TEMP channel.

Signed-off-by: Thomas Schmid <[email protected]>

Author: rckTom