tf-a-lts2.8-gerrit-tforg-l1/l2: Use mbedTLS 2.28.1

Following tf-a-lts2.8-main.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I4f94503680ef8c302392a1e055569bffe4f6dcfe
diff --git a/tf-a-lts2.8-gerrit-tforg-l1.yaml b/tf-a-lts2.8-gerrit-tforg-l1.yaml
index 229558e..8c642ee 100644
--- a/tf-a-lts2.8-gerrit-tforg-l1.yaml
+++ b/tf-a-lts2.8-gerrit-tforg-l1.yaml
@@ -54,6 +54,9 @@
             name: CI_REFSPEC
             default: '+refs/heads/lts-v2.8:refs/remotes/origin/lts-v2.8'
         - string:
+            name: MBEDTLS_URL
+            default: 'https://github.com/Mbed-TLS/mbedtls/archive/mbedtls-2.28.1.tar.gz'
+        - string:
             name: SHARE_FOLDER
             default: '/srv/shared/prod/${JOB_NAME}/${BUILD_NUMBER}'
             description: 'Folder containing shared repositories for downstream pipeline jobs'