ARM: at91: fix at91_extern_irq usage for non-dt boards

Since 4b68520dc0ec96153bc0d87bca5ffba508edfcf
ARM: at91: add AIC5 support

we allocate the at91_extern_irq.

This patch makes it static and stores the non-dt extern irq in the soc
structure. It is then possible to use a at91_get_extern_irq() function
to get the value for outside of the irq driver. It is useful for passing
its value to at91_aic_init().

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
[nicolas.ferre@atmel.com: rework commit message]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/irq.c b/arch/arm/mach-at91/irq.c
index e0ca591..3d192c5 100644
--- a/arch/arm/mach-at91/irq.c
+++ b/arch/arm/mach-at91/irq.c
@@ -232,7 +232,14 @@
 	at91_aic_write(AT91_AIC5_EOICR, 0);
 }
 
-unsigned long *at91_extern_irq;
+static unsigned long *at91_extern_irq;
+
+u32 at91_get_extern_irq(void)
+{
+	if (!at91_extern_irq)
+		return 0;
+	return *at91_extern_irq;
+}
 
 #define is_extern_irq(hwirq) test_bit(hwirq, at91_extern_irq)