[POWERPC] of_serial: Ignore unknown serial port

Current of_serial driver assumes unknown serial port to be 8250.  But
this behavior may cause fatal problems when the serial port is not
8250.  This corrects probe routine to ignore unknown serial port.
Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

drivers/serial/of_serial.c

@@ -75,15 +75,13 @@ static int __devinit of_platform_serial_probe(struct of_device *ofdev,
 		goto out;
 
 	switch (port_type) {
-	case PORT_UNKNOWN:
-		dev_info(&ofdev->dev, "Unknown serial port found, "
-			"attempting to use 8250 driver\n");
-		/* fallthrough */
 	case PORT_8250 ... PORT_MAX_8250:
 		ret = serial8250_register_port(&port);
 		break;
 	default:
 		/* need to add code for these */
+	case PORT_UNKNOWN:
+		dev_info(&ofdev->dev, "Unknown serial port found, ignored\n");
 		ret = -ENODEV;
 		break;
 	}