motion: Alter ec_rate to prevent samples without data
motion: Alter ec_rate to prevent samples without data

If EC sampling rate is close to sensor rate, decrease sampling frequency
by 5% to prevent samples by the EC without data.
It can happen when the clocks are slightly different and get
unsynchronized.

BRANCH=smaug
BUG=b:24367625
TEST=Ran cts.SingleSensorTests overnight without error.

Change-Id: Iab5e578763171411eb474e1e717167c8e1ef7ecf
Signed-off-by: Gwendal Grignou <190c5a5edfcf62e0246559bf31fa7548674de3ad@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/312985
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics