[IA64] Minor cleanups - remove unnecessary function prototype in irq.h

The function prototype for handl_IRQ_event() in include/asm-ia64/irq.h
is no longer needed. This patch removes it.
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/irq.h

@@ -36,8 +36,4 @@ extern void move_irq(int irq);
 #define move_irq(irq)
 #endif
 
-struct irqaction;
-struct pt_regs;
-int handle_IRQ_event(unsigned int, struct pt_regs *, struct irqaction *);
-
 #endif /* _ASM_IA64_IRQ_H */