fix parse policy

Author: Alevsk

restapi/admin_policies.go

@@ -158,11 +158,7 @@ func getRemovePolicyResponse(params admin_api.RemovePolicyParams) error {
 // policy must be string in json format, in the future this will change
 // to a Policy struct{} - https://github.com/minio/minio/issues/9171
 func addPolicy(ctx context.Context, client MinioAdmin, name, policy string) (*models.Policy, error) {
-	policyB, err := json.Marshal(policy)
-	if err != nil {
-		return nil, err
-	}
-	iamp, err := iampolicy.ParseConfig(bytes.NewReader(policyB))
+	iamp, err := iampolicy.ParseConfig(bytes.NewReader([]byte(policy)))
 	if err != nil {
 		return nil, err
 	}