ARM: at91: make rtt register base soc independant

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/at91sam9rl_devices.c b/arch/arm/mach-at91/at91sam9rl_devices.c
index 34fe5dd..f9b423b 100644
--- a/arch/arm/mach-at91/at91sam9rl_devices.c
+++ b/arch/arm/mach-at91/at91sam9rl_devices.c
@@ -685,8 +685,8 @@
 
 static struct resource rtt_resources[] = {
 	{
-		.start	= AT91_BASE_SYS + AT91_RTT,
-		.end	= AT91_BASE_SYS + AT91_RTT + SZ_16 - 1,
+		.start	= AT91SAM9RL_BASE_RTT,
+		.end	= AT91SAM9RL_BASE_RTT + SZ_16 - 1,
 		.flags	= IORESOURCE_MEM,
 	}
 };