greybus: uart fix missing negation on DTR setting

The unset the DTR flag is missing "~"

Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index aa28ce5..75fa527 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -375,7 +375,7 @@
 
 	if (C_BAUD(tty) == B0) {
 		newline.rate = gb_tty->line_coding.rate;
-		newctrl &= GB_UART_CTRL_DTR;
+		newctrl &= ~GB_UART_CTRL_DTR;
 	} else if (termios_old && (termios_old->c_cflag & CBAUD) == B0) {
 		newctrl |= GB_UART_CTRL_DTR;
 	}