Second set of IIO fixes for the 4.9 cycle.
Interestingly scale related fixes for accelerometers at both ends of
the range. Obviously more varied devices turning up than we've seen before!
* ad5933
- fix an uninitialized value in a return case that is winding up GCC.
* hid sensors
- missing pm function prevents hid rotations sensors from working on newer
ISH hubs (works by luck on older ones)
- increase of scale precision needed to fix a case where on a yoga 260
the reported scale is 0 (presumably a high precision but very low g sensor).
* st_sensors
- fix an issue seen with the hs3lis331dl where the range is much greater
than previous devices (100's of g) and hence the per bit scale is greater
than 1.