Merge pull request riscv#2686 from riscv/2685-missing-cache_block_size-normative-rule

Added CACHE_BLOCK_SIZE norm rule

Author: james-ball-qualcomm

normative_rule_defs/cmo.yaml

@@ -9,6 +9,10 @@ $schema: "../docs-resources/schemas/defs-schema.json#"
 chapter_name: Cache Manage Ops
 
 normative_rule_definitions:
+  - name: CACHE_BLOCK_SIZE
+    tag: "norm:cache_block_size"
+    impl-def-behavior: true
+
   # Memory ordering rules
   - name: PPO_overlap
     summary: PPO overlapping address rule for CMO instructions