serial: 8250_early: Fix setup() error code

If parsing failed to decode a valid uart addr, return -ENODEV instead
of success. Although setup_earlycon() will detect the failure anyway
(because the write() method has not been set), that behavior is not
obvious and should not be relied on.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_early.c

@@ -146,7 +146,7 @@ static int __init early_serial8250_setup(struct earlycon_device *device,
 					 const char *options)
 {
 	if (!(device->port.membase || device->port.iobase))
-		return 0;
+		return -ENODEV;
 
 	if (!device->baud) {
 		struct uart_port *port = &device->port;