[reggen] Promote missing CM annotation warning to error

Fixes #10071

Signed-off-by: Michael Schaffner <[email protected]>

util/reggen/countermeasure.py

@@ -207,9 +207,8 @@ def check_annotation_list(what: str,
 
         # Is there anything in the Hjson that isn't described in the RTL?
         for name in hjson_set - rtl_set:
-            log.warning("Countermeasure {} is referenced in the Hjson of the "
-                        "{}, but doesn't appear in the RTL."
-                        .format(name, what))
-
-        # TODO(#10071): Once all designs are annotated, generate a RuntimeError
-        #               if we saw anything in the loop above.
+            log.error("Countermeasure {} is referenced in the Hjson of the "
+                      "{}, but doesn't appear in the RTL."
+                      .format(name, what))
+            raise RuntimeError('One or more unknown countermeasures '
+                               'are not annotated in RTL.')