serial: uartps: Add TACTIVE check in cdns_uart_tx_empty function

Make sure that all bytes are transmitted out of Uart by monitoring
CDNS_UART_SR_TACTIVE bit as well.
Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Acked-by: Maarten Brock <m.brock@vanmierlo.com>
Link: https://lore.kernel.org/r/e2514818af5973be291cc117d07739f068b71639.1584610774.git.shubhrajyoti.datta@xilinx.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -650,8 +650,8 @@ static unsigned int cdns_uart_tx_empty(struct uart_port *port)
 	unsigned int status;
 
 	status = readl(port->membase + CDNS_UART_SR) &
-				CDNS_UART_SR_TXEMPTY;
-	return status ? TIOCSER_TEMT : 0;
+		       (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE);
+	return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0;
 }
 
 /**