hail app: adc samples in upper bits
hail app: adc samples in upper bits

The ADC always returns samples as 16 bits, even though the ADC may use
fewer bits. This fixes the calculation since the 12 bits of SAM4L adc
will always be the upper 12 bits.

tock/libtock-c,tock/libtock-c,tock/libtock-c