[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/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 7700e23..2a70af4 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -678,7 +678,7 @@
 int migrate_platform_irqs(unsigned int cpu)
 {
 	int new_cpei_cpu;
-	irq_desc_t *desc = NULL;
+	struct irq_desc *desc = NULL;
 	const struct cpumask *mask;
 	int 		retval = 0;