Fetch and unzip Linaro's platform files

Currently, the builders.sh [1] script fetches Linaro's platform files
everytime a job runs but this can be avoided if the latter are already
present on the image.

[1] https://git.trustedfirmware.org/ci/tf-a-job-configs.git/tree/tf-a-builder/builders.sh

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I8736a73231111ae3304965268723b431013ab69d
1 file changed