iommu: dmar: Provide arch specific irq allocation

ia64 and x86 share this driver. x86 is moving to a different irq
allocation and ia64 keeps its private irq_create/destroy stuff.

Use macros to redirect to one or the other. Yes, macros to avoid
include hell.

Signed-off-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Grant Likely <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Fenghua Yu <[e-mail]>
Acked-by: Joerg Roedel <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Thomas Gleixner <[e-mail]>

arch/ia64/include/asm/irq_remapping.h

···
 #ifndef __IA64_INTR_REMAPPING_H
 #define __IA64_INTR_REMAPPING_H
 #define irq_remapping_enabled 0
+#define dmar_alloc_hwirq	create_irq
+#define dmar_free_hwirq		destroy_irq
 #endif

arch/x86/include/asm/irq_remapping.h

···
 }
 #endif /* CONFIG_IRQ_REMAP */
 
+#define dmar_alloc_hwirq()	irq_alloc_hwirq(-1)
+#define dmar_free_hwirq		irq_free_hwirq
+
 #endif /* __X86_IRQ_REMAPPING_H */

drivers/iommu/dmar.c

···
 	if (iommu->irq) {
 		free_irq(iommu->irq, iommu);
 		irq_set_handler_data(iommu->irq, NULL);
-		destroy_irq(iommu->irq);
+		dmar_free_hwirq(iommu->irq);
 	}
 
 	if (iommu->qi) {
···
 	if (iommu->irq)
 		return 0;
 
-	irq = create_irq();
+	irq = dmar_alloc_hwirq();
 	if (irq <= 0) {
 		pr_err("IOMMU: no free vectors\n");
 		return -EINVAL;
···
 	if (ret) {
 		irq_set_handler_data(irq, NULL);
 		iommu->irq = 0;
-		destroy_irq(irq);
+		dmar_free_hwirq(irq);
 		return ret;
 	}