CHERRY_PICK: hardware_EC: Fix bug of testing fan speed.

Fan speed test should check that fan speed reading is in
[target_speed - error_margin, target_speed + error_margin].

BUG=chrome-os-partner:19278
TEST=manual

Original Change-Id: Ie4a3b1ce14379734f6cb8bc0e40c9740cf6716d3
Original Reviewed-on: https://gerrit.chromium.org/gerrit/38193
Original Tested-by: Shuo-Peng Liao <deanliao@chromium.org>
Original Reviewed-by: Vic Yang <victoryang@chromium.org>
Original Commit-Ready: Shuo-Peng Liao <deanliao@chromium.org>

Change-Id: I24adc8b24c8ff3ffab188b545f3bb2a8b626f96c
Reviewed-on: https://gerrit.chromium.org/gerrit/50599
Commit-Queue: Bowgo Tsai <bowgotsai@chromium.org>
Reviewed-by: Bowgo Tsai <bowgotsai@chromium.org>
Tested-by: Bowgo Tsai <bowgotsai@chromium.org>
1 file changed