serial: meson: fix setting number of stop bits

The stop bit value as to be or'ed, so far this worked only just by chance
because AML_UART_STOP_BIN_1SB is 0.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/meson_uart.c

@@ -355,7 +355,7 @@ static void meson_uart_set_termios(struct uart_port *port,
 	if (cflags & CSTOPB)
 		val |= AML_UART_STOP_BIN_2SB;
 	else
-		val &= ~AML_UART_STOP_BIN_1SB;
+		val |= AML_UART_STOP_BIN_1SB;
 
 	if (cflags & CRTSCTS)
 		val &= ~AML_UART_TWO_WIRE_EN;