Since we're about to update the tool, use a fixed version for this
legacy branch of cca-buildroot-external

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>