poppy: fix accel/gyro rotation matrix
poppy: fix accel/gyro rotation matrix

The matrix was not correct and sensor would report -1G along the Z axis
while on a flat surface.

BUG=chrome-os-partner:63021
BRANCH=none
TEST=Check in ARC++ AIDA64 the gravity data is reported correctly along
the Z axis.

Change-Id: I0ddbf40876746432c640f547a5efede3a07c6eec
Signed-off-by: Gwendal Grignou <190c5a5edfcf62e0246559bf31fa7548674de3ad@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/444066
Tested-by: Rajat Jain <03f78e80d6c0fa76460c12a4ac7e68e277caf7a0@chromium.org>
Reviewed-by: Rajat Jain <03f78e80d6c0fa76460c12a4ac7e68e277caf7a0@chromium.org>

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