ARM: at91: sparse irq support

Enable sparse irq support for multisoc image. It involves to add the
NR_IRQS_LEGACY offset to static SoC irq number definitions since NR_IRQS_LEGACY
irq descs are allocated before AIC requests irq descs allocation.
Move NR_AIC_IRQS macro to a more appropiate place with the purpose to
remove mach/irqs.h later.

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/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
index a94758b..ffc0957 100644
--- a/arch/arm/mach-at91/at91sam926x_time.c
+++ b/arch/arm/mach-at91/at91sam926x_time.c
@@ -137,7 +137,7 @@
 	.name		= "at91_tick",
 	.flags		= IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 	.handler	= at91sam926x_pit_interrupt,
-	.irq		= AT91_ID_SYS,
+	.irq		= NR_IRQS_LEGACY + AT91_ID_SYS,
 };
 
 static void at91sam926x_pit_reset(void)