driver: bmi160: Preserve the timestamp before releasing interrupt
driver: bmi160: Preserve the timestamp before releasing interrupt

Collect timestamp before resetting the interrupt line:
After reading, it is possible for the timestamp to change,
before we can process the FIFO.

BUG=b:67743747
BRANCH=scarlet
TEST=CtsHardwareTestCases

Change-Id: I283f8efb1098a38c76caf326b6416a386ab221cd
Signed-off-by: Gwendal Grignou <190c5a5edfcf62e0246559bf31fa7548674de3ad@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1137438
Commit-Ready: Alexandru M Stan <1784cbba6d7675b1eba55eaefe41c7672ad9da3b@chromium.org>
Tested-by: Alexandru M Stan <1784cbba6d7675b1eba55eaefe41c7672ad9da3b@chromium.org>
Reviewed-by: Alexandru M Stan <1784cbba6d7675b1eba55eaefe41c7672ad9da3b@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec