doc: Add tf-m-tests repo dependency

The doc build needs tf-m test repo include.

Signed-off-by: Karl Zhang <karl.zhang@arm.com>
Change-Id: Ie36bf147436e0df78cb27a2eea440aaaceb9d845
diff --git a/jenkins/build-docs.jpl b/jenkins/build-docs.jpl
index bc284b2..c759fb1 100644
--- a/jenkins/build-docs.jpl
+++ b/jenkins/build-docs.jpl
@@ -54,6 +54,20 @@
     set -e
     unzip -o -d CMSIS_5 cmsis.pack
     """
+    dir("tf-m-tests") {
+      checkout(
+        changelog: false,
+        poll: false,
+        scm: [
+          $class: 'GitSCM',
+          branches: [[name: 'FETCH_HEAD']],
+          userRemoteConfigs: [[
+            refspec: '$TFM_TESTS_REFSPEC',
+            url: params.TFM_TESTS_URL
+          ]]
+        ]
+      )
+    }
   }
   try {
     verify = 1