altera_uart: Fixup type usage of port flags

port->flags is of type upf_t, which corresponds to UPF_* flags.

ASYNC_BOOT_AUTOCONF is an unsigned integer, which happen to
be the same as UPF_BOOT_AUTOCONF.

Signed-off-by: Anton Vorontsov <[e-mail]>
Acked-by: Tobias Klauser <[e-mail]>
Cc: Alan Cox <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/serial/altera_uart.c

···
 		port->iotype = SERIAL_IO_MEM;
 		port->irq = platp[i].irq;
 		port->uartclk = platp[i].uartclk;
-		port->flags = ASYNC_BOOT_AUTOCONF;
+		port->flags = UPF_BOOT_AUTOCONF;
 		port->ops = &altera_uart_ops;
 		port->private_data = platp;
 	}
···
 	port->iotype = SERIAL_IO_MEM;
 	port->uartclk = platp->uartclk;
 	port->ops = &altera_uart_ops;
-	port->flags = ASYNC_BOOT_AUTOCONF;
+	port->flags = UPF_BOOT_AUTOCONF;
 	port->private_data = platp;
 
 	uart_add_one_port(&altera_uart_driver, port);