motion: Fix the number of sample to collect in motion task
motion: Fix the number of sample to collect in motion task

AP could collect samples while motion task was still adding timestamp.
A data stream not ending with a timestamp can lead to timestamp error in
the kernel.
This is espcially true if the motion task interrupt the AP back to back,
when sensor ODR changes for instance.

BRANCH=smaug
BUG=b:24367625
TEST=Run android.hardware.cts.SingleSensorTests

Change-Id: I5820216a2cfc0a869db7dc5ef75d4be126a53b4f
Signed-off-by: Gwendal Grignou <190c5a5edfcf62e0246559bf31fa7548674de3ad@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/313640
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

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