libpayload: Use #ifdef for CONFIG_* checks

Libpayload uses the linux kernel's config style, where CONFIG_* defines
don't get written for unset tristates.

Change-Id: I3f832cf86bca9a1e153d96af4bf6434a19eba2f6
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/1847
Tested-by: build bot (Jenkins)
Reviewed-by: Anton Kochkov <anton.kochkov@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

payloads/libpayload/arch/powerpc/main.c

@@ -47,8 +47,9 @@ void start_main(void)
 	extern int main(int argc, char **argv);
 
 	/* Optionally set up the consoles. */
-	if (!CONFIG_SKIP_CONSOLE_INIT)
-		console_init();
+#ifndef CONFIG_SKIP_CONSOLE_INIT
+	console_init();
+#endif
 
 	/* Gather system information. */
 	lib_get_sysinfo();