serial/core: Fix too big allocation for attribute member

Current code allocates too much data for tty_groups member of uart_port struct,
so fix it.
Signed-off-by: NYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial_core.c

@@ -2618,7 +2618,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 	if (uport->attr_group)
 		num_groups++;
 
-	uport->tty_groups = kcalloc(num_groups, sizeof(**uport->tty_groups),
+	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
 				    GFP_KERNEL);
 	if (!uport->tty_groups) {
 		ret = -ENOMEM;