serial: 8250_pxa: hide early console setup when disabled

The newly added pxa glue driver for 8250 supports console output, but
fails to build if the 8250 console is disabled:

drivers/tty/serial/8250/8250_pxa.o: In function `early_serial_pxa_setup':
8250_pxa.c:(.init.text+0x50): undefined reference to `early_serial8250_setup'

This adds an #ifdef like the other glue drivers have it.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_pxa.c

@@ -172,6 +172,7 @@ static struct platform_driver serial_pxa_driver = {
 
 module_platform_driver(serial_pxa_driver);
 
+#ifdef CONFIG_SERIAL_8250_CONSOLE
 static int __init early_serial_pxa_setup(struct earlycon_device *device,
 				  const char *options)
 {
@@ -184,6 +185,7 @@ static int __init early_serial_pxa_setup(struct earlycon_device *device,
 	return early_serial8250_setup(device, NULL);
 }
 OF_EARLYCON_DECLARE(early_pxa, "mrvl,pxa-uart", early_serial_pxa_setup);
+#endif
 
 MODULE_AUTHOR("Sergei Ianovich");
 MODULE_LICENSE("GPL");