Add basic support for TI HDC20XX series (e.g. HDC2010, HDC2021, HDC2022,
HDC2080). It is able to get temperature and humidity in the default
14-bit resolution. Triggers, resolution selection, interrupt line, auto
measurement mode are currently not supported.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
