Code for hard iron calibration: Every seconds (or faster if enough
samples), find a sphere that fit the compass data.
Based on Android code.
BRANCH=smaug
BUG=chrome-os-partner:39900
TEST=Check hard-iron bias is removed. Works better outside.
Change-Id: Iab479d5113b6560b4f01b0fd87373d2eecdb9b54
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/299583
Reviewed-by: Anton Staaf <robotboy@chromium.org>
