platform/chrome: cros_ec_trace: Fix format warnings

Fix printf format issues in new tracing events.

Fixes: 81431824 ("platform/chrome: cros_ec_trace: Add fields to command traces")

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Link: https://lore.kernel.org/r/20210830180050.2077261-1-gwendal@chromium.org


Signed-off-by: Benson Leung <bleung@chromium.org>