CI: add LTS versions for testing

Add a CI test for the LTS versions of recipes currently supported.
Use fvp-base, since that provides good coverage and is being used for
the latest version testing.

Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -190,6 +190,8 @@ fvp-base:
         TESTING: testimage
       - FIRMWARE: [u-boot, edk2]
         TESTING: testimage
+      - LTS: lts-revisions
+        TESTING: testimage
       - KERNEL: linux-yocto-dev
         LATEST: latest-revisions
         TESTING: testimage

ci/lts-revisions.yml

@@ -0,0 +1,10 @@
+# yaml-language-server: $schema=https://raw.githubusercontent.com/siemens/kas/master/kas/schema-kas.json
+
+header:
+  version: 14
+
+local_conf_header:
+  latest_revisions: |
+    PREFERRED_VERSION_trusted-firmware-a ?= "2.10.%"
+    PREFERRED_VERSION_tf-a-tests ?= "2.10.%"
+    PREFERRED_VERSION_trusted-firmware-m ?= "2.1.%"