Address comments: clean up code style in parse_params.rb

Author: TySpring

lib/grape-swagger/doc_methods/parse_params.rb

@@ -64,9 +64,8 @@ def document_array_param(value_type)
           if value_type[:is_array]
             if value_type[:documentation].present?
               param_type = value_type[:documentation][:param_type]
-              if (doc_type = value_type[:documentation][:type])
-                type = GrapeSwagger::DocMethods::DataType.mapping(doc_type)
-              end
+              doc_type = value_type[:documentation][:type]
+              type = GrapeSwagger::DocMethods::DataType.mapping(doc_type) if doc_type
             end
             array_items = { 'type' => type || value_type[:data_type] }