Requantize by resolution / 8

Requantizing by resolution / 4 causing the calibration error / min on
calibrated sensors to be too high. Changing to 8 reduces that error
enough to keep sensor accuracy below our thresholds.

Bug: 158451802
Test: Verify that calibration error / min is low
Change-Id: I350980734cc0a46f4f06878371e0d9bd7ce07de0