scripts/dtc: Update to upstream version 9d3649bd3be245c9

Sync dtc with upstream as of commit 9d3649bd3be2 (Add testcases for
fdt_path_offset_namelen()).

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: devicetree@vger.kernel.org