fixed conflicting prefix

Author: raaghavendrakra-arista

src/sonic-yang-models/yang-models/sonic-tc-dscp-map.yang

@@ -4,7 +4,7 @@ module sonic-tc-dscp-map {
 
     namespace "http://github.com/sonic-net/sonic-tc-dscp-map";
 
-    prefix dtm;
+    prefix tdm;
 
     import sonic-types {
         prefix stypes;