TF-A: create /arm folder and chown to buildslave

There is a temporary need to create softlinks (to be created at
runtime, by CI jobs) on top of /arm folder, these pointing to TOOLS_DIR
folder, so paths at CI scripts' tf_config folder, currently pointing to
/arm are not required to change at this point. Ultimately, the reason
not to change the /arm paths at CI scripts is that Arm CI is running
and cannot be stopped, so once CR01 migration is over and all jobs
running, then Arm CI can fully move to Open CI. One this happens, this
patch can be reverted.

CR01 https://developer.trustedfirmware.org/w/collaboration/openci/

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Idb9d4a70bb3d134df65cc250cd862dcec87f28d5
diff --git a/bionic-amd64-tf-a-build/Dockerfile b/bionic-amd64-tf-a-build/Dockerfile
index 1a9ded6..502a09f 100644
--- a/bionic-amd64-tf-a-build/Dockerfile
+++ b/bionic-amd64-tf-a-build/Dockerfile
@@ -74,12 +74,13 @@
     echo "buildslave:$BUILDSLAVE_PASSWORD" | chpasswd ;\
     echo 'buildslave ALL = NOPASSWD: ALL' > /etc/sudoers.d/jenkins ;\
     chmod 0440 /etc/sudoers.d/jenkins ;\
-    mkdir -p /var/run/sshd ${TOOLS_DIR} ;\
+    # FIXME: add /arm as a temporary workaround until ARM CI moves to Open CI paths
+    mkdir -p /var/run/sshd ${TOOLS_DIR} /arm ;\
     # Run shell script(s) to install files, toolchains, etc...
     bash -ex /tmp/tf-dependencies.install ;\
     bash -ex /tmp/tf-environment.install ;\
     # Fix permissions
-    chown -R buildslave:buildslave ${TOOLS_DIR} /usr/share/plantuml /nfs/downloads/linaro ;\
+    chown -R buildslave:buildslave ${TOOLS_DIR} /usr/share/plantuml /nfs/downloads/linaro /arm ;\
     # Cleanup
     apt clean ;\
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*