ARM: at91: don't provide dt init code for at91x40

at91x40 has no support for device tree, but Kconfig allows
us to enable CONFIG_OF anyway, causing a link error in the
at91 reset controller initialization.

The easiest fix is to adapt the existing #ifdef to omit
the broken code on at91x40 where it is never called anyway.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>

arch/arm/mach-at91/setup.c

@@ -351,7 +351,7 @@ void __init at91_ioremap_matrix(u32 base_addr)
 		panic("Impossible to ioremap at91_matrix_base\n");
 }
 
-#if defined(CONFIG_OF)
+#if defined(CONFIG_OF) && !defined(CONFIG_ARCH_AT91X40)
 static struct of_device_id rstc_ids[] = {
 	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9_alt_restart },
 	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },