tf-a-lts2.8-builder: Further sync with tf-a-builder

Added CI_REFSPEC param from upstream to minimize differences.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ia526a6321aa2fa131dbf14b72a739878da359be1
diff --git a/tf-a-lts2.8-builder.yaml b/tf-a-lts2.8-builder.yaml
index f2e394a..ad82acd 100644
--- a/tf-a-lts2.8-builder.yaml
+++ b/tf-a-lts2.8-builder.yaml
@@ -43,6 +43,9 @@
             name: TFTF_GERRIT_REFSPEC
             default: '+refs/heads/master:refs/remotes/origin/master'
         - string:
+            name: CI_REFSPEC
+            default: '+refs/heads/master:refs/remotes/origin/master'
+        - string:
             name: DOCKER_REGISTRY
             default: '987685672616.dkr.ecr.us-east-1.amazonaws.com'
         - string: