Introduce bionic-amd64-tf-a-build dockerfile and build infrastructure

There is a need to have separate docker images, each one targeted for
specific project, i.e. TF-A, TF-M and Hafnium, otherwise some
toolchain triplets may collide, i.e arm-none-eabi for M-Profiles and
arm-none-eabi for A-profiles, or there could be different toolchain
versions requirements as seen in [1,2]. This commit introduce the definition of
the docker image (Dockerfile), its dependencies and build script for
the TF-A project. At this moment, the only difference between TF-A and
TF-M dockerfile is the arm-none-eabi, each targeting its profile.

As a consequence of this new image, the corresponding project-name is
now part of the image, leading to two new images:

* trustedfirmware/ci-amd64-tf-a-ubuntu:bionic
* trustedfirmware/ci-amd64-tf-m-ubuntu:bionic

[1] https://trustedfirmware-a.readthedocs.io/en/latest/getting_started/prerequisites.html?highlight=arm-none-eabi-gcc#toolchain

[2] https://ci.trustedfirmware.org/view/TF-M/job/tf-m-build-docs-nightly/lastStableBuild/artifact/trusted-firmware-m/build/install/doc/user_guide/html/docs/getting_started/tfm_sw_requirement.html

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Ia36551b29818d57dc08fb839032a16474dc59b79
diff --git a/bionic-amd64-tf-m-build/build.sh b/bionic-amd64-tf-m-build/build.sh
index 2edbccd..d2bf20c 100755
--- a/bionic-amd64-tf-m-build/build.sh
+++ b/bionic-amd64-tf-m-build/build.sh
@@ -13,9 +13,10 @@
 
 DISTRIBUTION=$(basename ${PWD} | cut -f1 -d '-')
 ARCHITECTURE=$(basename ${PWD} | cut -f2 -d '-')
+PROJECT=$(basename ${PWD} | cut -f3 -d '-')-$(basename ${PWD} | cut -f4 -d '-')
 
 cp -a ../setup-sshd .
 
-image=trustedfirmware/ci-${ARCHITECTURE}-ubuntu:${DISTRIBUTION}
+image=trustedfirmware/ci-${ARCHITECTURE}-${PROJECT}-ubuntu:${DISTRIBUTION}
 docker build --pull --tag=$image .
 echo $image > .docker-tag