CODE-COVERAGE: Adds tf-m-extras pull to this job

Change-Id: Iba3935e96f14f33ef001471bde2bfdd3d1ffda03
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/tf-m-code-coverage.yaml b/tf-m-code-coverage.yaml
index 40c458f..2aa797a 100644
--- a/tf-m-code-coverage.yaml
+++ b/tf-m-code-coverage.yaml
@@ -118,6 +118,17 @@
             TAG_NAME                 : Pick up a tagged version
             full commit hash         : Pick up a specific commit
       - string:
+          name: 'TFM_EXTRAS_URL'
+          default: 'https://git.trustedfirmware.org/TF-M/tf-m-extras.git'
+      - string:
+          name: 'TFM_EXTRAS_REFSPEC'
+          default: ''
+          description: |
+            Specify which tf-m-extras version to use
+            refs/heads/<branch_name> : Pick up latest HEAD on branch
+            TAG_NAME                 : Pick up a tagged version
+            full commit hash         : Pick up a specific commit
+      - string:
           name: 'PSA_ARCH_TESTS_URL'
           default: 'https://git.trustedfirmware.org/mirror/psa-arch-tests.git'
       - string: