test: motionsense fifo: Fix time units
test: motionsense fifo: Fix time units

Convert time units in the test from ns to us

BRANCH=none
BUG=none
TEST=make run-motion_sense_fifo

Signed-off-by: Yuval Peress <50dc11c009bd4d7e9d9d15a383c1743ce5ee82ef@chromium.org>
Change-Id: I345ce43945d2bcd743347296430d76c2992a953a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2871056
Reviewed-by: Gwendal Grignou <190c5a5edfcf62e0246559bf31fa7548674de3ad@chromium.org>

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