ARM: at91: fix rtc-at91sam9 irq issue due to sparse irq support

AT91_ID_SYS as virq is incorrect because of spare irq support which
introduces NR_IRQS_LEGACY offset. It modifies rtc-at91sam9 driver in
order to get irq from resources.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-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 f09fff9..b3d365d 100644
--- a/arch/arm/mach-at91/at91sam9rl_devices.c
+++ b/arch/arm/mach-at91/at91sam9rl_devices.c
@@ -688,6 +688,8 @@
 		.flags	= IORESOURCE_MEM,
 	}, {
 		.flags	= IORESOURCE_MEM,
+	}, {
+		.flags  = IORESOURCE_IRQ,
 	}
 };
 
@@ -705,10 +707,12 @@
 	 * The second resource is needed:
 	 * GPBR will serve as the storage for RTC time offset
 	 */
-	at91sam9rl_rtt_device.num_resources = 2;
+	at91sam9rl_rtt_device.num_resources = 3;
 	rtt_resources[1].start = AT91SAM9RL_BASE_GPBR +
 				 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR;
 	rtt_resources[1].end = rtt_resources[1].start + 3;
+	rtt_resources[2].start = NR_IRQS_LEGACY + AT91_ID_SYS;
+	rtt_resources[2].end = NR_IRQS_LEGACY + AT91_ID_SYS;
 }
 #else
 static void __init at91_add_device_rtt_rtc(void)