[IA64] remove obsolete irq_desc_t typedef

The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t) have
been kept around for migration reasons.  After more than two years it's
time to remove them finally.

This patch cleans up one of the remaining users.  When all such patches
hit mainline we can remove the defines and typedefs finally.

Impact: cleanup

Convert the last remaining users and remove the typedef.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/include/asm/hw_irq.h b/arch/ia64/include/asm/hw_irq.h
index 5c99cbc..276f9d4 100644
--- a/arch/ia64/include/asm/hw_irq.h
+++ b/arch/ia64/include/asm/hw_irq.h
@@ -146,7 +146,7 @@
  * Default implementations for the irq-descriptor API:
  */
 
-extern irq_desc_t irq_desc[NR_IRQS];
+extern struct irq_desc irq_desc[NR_IRQS];
 
 #ifndef CONFIG_IA64_GENERIC
 static inline ia64_vector __ia64_irq_to_vector(int irq)