mxs-auart: count FIFO overrun errors

The mxs-auart driver does not count FIFO overrun errors. These errors never
appear in /proc/tty/driver/ttyAPP. This is because the OERR status bit is
masked by read_status_mask in the rx interrupt function, but the
AUART_STAT_OERR bit is never set in read_status_mask. The patch enables the
counting of overrun errors.
Signed-off-by: Wolfgang Ocker <weo@reccoware.de>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mxs-auart.c

@@ -1016,7 +1016,7 @@ static void mxs_auart_settermios(struct uart_port *u,
 			ctrl |= AUART_LINECTRL_EPS;
 	}
 
-	u->read_status_mask = 0;
+	u->read_status_mask = AUART_STAT_OERR;
 
 	if (termios->c_iflag & INPCK)
 		u->read_status_mask |= AUART_STAT_PERR;