Adding v8.2.1A modules (#1685)

* Add Arrcus YANG modules.

* Added v8.2.1A YANG modules.

Author: mjethanandani

vendor/arrcus/arcos/check.sh

@@ -13,7 +13,7 @@
 platform_dir="vendor/arrcus/"
 
 # NOTE: please just have the directories you are checking here
-to_check="arcos/v521"
+to_check="arcos/v821"
 
 debug=0