dockerfile-template: install packages to support ssh-server

There is a need to recover code coverage logs from FVP containers [1] so
install required packages. Also, use docker ENV variables in the
dockerfile-template to hold packages dependencies, making it
cleaner the package installation phase.

[1] https://review.trustedfirmware.org/c/ci/tf-a-ci-scripts/+/9632

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Iafb730c26412954026221be54d39081aa7dd2e26
diff --git a/script/docker/fvp/Makefile b/script/docker/fvp/Makefile
index 8ffc9c1..da7c327 100644
--- a/script/docker/fvp/Makefile
+++ b/script/docker/fvp/Makefile
@@ -23,6 +23,7 @@
 	rm -rf $(WORKSPACE)/$${tag} && \
 	mkdir -p $(WORKSPACE)/$${tag} && \
 	cp $@ $(WORKSPACE)/$${tag} && \
+        cp setup-sshd $(WORKSPACE)/$${tag} && \
 	./create-model-dockerfile.sh $${tarball} $(WORKSPACE)/$${tag} && \
 	docker build --tag fvp:$${tag} $(WORKSPACE)/$${tag} > /dev/null && \
 	echo "Docker image created" && \