The lradc architecture of the stmp3600 is rather different:
only channels 6 and 7 have configurable source and we need to
take care when allocating channels so that we can actually
measure the right channel! Delegate die temperature sensing to
the power block on stmp3600.
Change-Id: I0860eb4ea98240facc3d4a19d61684eca5f630cc
Rework code to be more useful:
- move battery channel init to lradc
- always init lradc from system (previously from adc)
- don't reserve channels for vddio, nmos or pmos
- implement external temperature sensing using current source
- use this for battery sensing on the Fuze+ (calibration needed)
Change-Id: I5f9a24b9243db7d1e6bdb16b84bc891e61d0c318
