[IA64] fix allnoconfig build

cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/arch/ia64/sn/kernel/irq.c b/arch/ia64/sn/kernel/irq.c
index 84d276a..392bf8a 100644
--- a/arch/ia64/sn/kernel/irq.c
+++ b/arch/ia64/sn/kernel/irq.c
@@ -23,7 +23,7 @@
 static void register_intr_pda(struct sn_irq_info *sn_irq_info);
 static void unregister_intr_pda(struct sn_irq_info *sn_irq_info);
 
-extern int sn_force_interrupt_flag;
+int sn_force_interrupt_flag = 1;
 extern int sn_ioif_inited;
 static struct list_head **sn_irq_lh;
 static spinlock_t sn_irq_info_lock = SPIN_LOCK_UNLOCKED; /* non-IRQ lock */