tfa-next: add commit linting job

For now a copy of tf-a-commitlint.yaml but with added SSH auth to the
Jenkinsfile to be able to fetch the commit messages.

Revert to tf-a-commitlint once SSH auth is no longer required.

Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
Change-Id: I5768d86dfef3884c2903cd50247224d7a84beca0
diff --git a/tf-a-main-tfa-next.yaml b/tf-a-main-tfa-next.yaml
index 028d7aa..24f1889 100644
--- a/tf-a-main-tfa-next.yaml
+++ b/tf-a-main-tfa-next.yaml
@@ -115,6 +115,16 @@
         SHARE_FOLDER=${SHARE_FOLDER}
         EOF
     - multijob:
+        name: Lint commit messages
+        condition: COMPLETED
+        projects:
+        - name: tf-a-commitlint-tfa-next
+          kill-phase-on: NEVER
+          predefined-parameters: |
+            REFSPEC=${GERRIT_REFSPEC}
+            REFNAME=${GERRIT_PATCHSET_REVISION}
+            REFNAME_BASE=origin/${GERRIT_BRANCH}
+    - multijob:
         name: Code formatting, static checks and lints
         condition: COMPLETED
         projects: