CI: use honister branch for meta-clang

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

ci/clang.yml

@@ -4,7 +4,7 @@ header:
 repos:
   meta-clang:
     url: https://github.com/kraj/meta-clang
-    refspec: master
+    refspec: honister
 
 local_conf_header:
   clang: |