Add driver for TCN75A temperature sensor. The following features are
supported:
- TCN75A oneshot mode, which allows single shot conversions with lower
power consumtion
- Resolution selection, up to 12 bit resolution (9 bit default)
- Triggering based on temperatue thresholds. If the TCN75A exits a set
threshold range, the application can be notified via a callback.
Signed-off-by: Daniel DeGrasse <daniel@degrasse.com>