serial: 8250: Decouple core from skip_txen_test module param

Prepare for 8250 split; initialize the port flags based on the
"skip_txen_test" module param to use the existing flag test.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_core.c

@@ -2253,7 +2253,7 @@ int serial8250_do_startup(struct uart_port *port)
 	   is variable. So, let's just don't test if we receive
 	   TX irq. This way, we'll never enable UART_BUG_TXEN.
 	 */
-	if (skip_txen_test || up->port.flags & UPF_NO_TXEN_TEST)
+	if (up->port.flags & UPF_NO_TXEN_TEST)
 		goto dont_test_tx_en;
 
 	/*
@@ -3196,6 +3196,9 @@ serial8250_register_ports(struct uart_driver *drv, struct device *dev)
 
 		up->port.dev = dev;
 
+		if (skip_txen_test)
+			up->port.flags |= UPF_NO_TXEN_TEST;
+
 		if (up->port.flags & UPF_FIXED_TYPE)
 			serial8250_init_fixed_type_port(up, up->port.type);
 
@@ -3663,6 +3666,9 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		if (up->port.dev)
 			uart->port.dev = up->port.dev;
 
+		if (skip_txen_test)
+			uart->port.flags |= UPF_NO_TXEN_TEST;
+
 		if (up->port.flags & UPF_FIXED_TYPE)
 			serial8250_init_fixed_type_port(uart, up->port.type);
 
@@ -3728,6 +3734,8 @@ void serial8250_unregister_port(int line)
 	uart_remove_one_port(&serial8250_reg, &uart->port);
 	if (serial8250_isa_devs) {
 		uart->port.flags &= ~UPF_BOOT_AUTOCONF;
+		if (skip_txen_test)
+			uart->port.flags |= UPF_NO_TXEN_TEST;
 		uart->port.type = PORT_UNKNOWN;
 		uart->port.dev = &serial8250_isa_devs->dev;
 		uart->capabilities = 0;