Cambia il tuo codice in:
DELIMITER $$
USE `db_test`$$
DROP PROCEDURE IF EXISTS `test_proc`$$
CREATE DEFINER=`root`@`localhost` PROCEDURE `test_proc`(IN newsInfoTable VARCHAR(100))
BEGIN
SET @sql_stam = CONCAT( 'SELECT news INTO @news FROM ',newsInfoTable
,' WHERE DATE(`date_time`) = CURDATE()' );
PREPARE s1 FROM @sql_stam;
SELECT @news;
END$$
DELIMITER ;