suffix enum name with classname to avoid conflict

fix #7300

Author: CatTail

modules/swagger-codegen/src/main/resources/go/model.mustache

@@ -13,7 +13,7 @@ const (
 	{{#enumVars}}
 	{{^-first}}
 	{{/-first}}
-	{{name}} {{{classname}}} = "{{{value}}}"
+	{{name}}_{{{classname}}} {{{classname}}} = "{{{value}}}"
 	{{/enumVars}}
 	{{/allowableValues}}
 ){{/isEnum}}{{^isEnum}}{{#description}}