focal-amd64-mbed-tls-host: create /var/run/sshd directory

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I2f93b99868c0e4296d4124313842cc0c201acaf6
diff --git a/focal-amd64-mbed-tls-host/Dockerfile b/focal-amd64-mbed-tls-host/Dockerfile
index d0a5287..f9c2b94 100644
--- a/focal-amd64-mbed-tls-host/Dockerfile
+++ b/focal-amd64-mbed-tls-host/Dockerfile
@@ -44,7 +44,7 @@
     chmod 0440 /etc/sudoers.d/jenkins ;\
     usermod -aG docker buildslave ;\
     ln -s $(which python3) /usr/bin/python ;\
-    mkdir -p /home/buildslave/workspace
+    mkdir -p /home/buildslave/workspace /var/run/sshd
 
 EXPOSE 22
 ENTRYPOINT ["/usr/sbin/setup-sshd"]