iommu/irq: Use amd_iommu_irq_ops if supported

Finally enable interrupt remapping for AMD systems.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

drivers/iommu/irq_remapping.c

@@ -51,6 +51,11 @@ early_param("intremap", setup_irqremap);
 void __init setup_irq_remapping_ops(void)
 {
 	remap_ops = &intel_irq_remap_ops;
+
+#ifdef CONFIG_AMD_IOMMU
+	if (amd_iommu_irq_ops.prepare() == 0)
+		remap_ops = &amd_iommu_irq_ops;
+#endif
 }
 
 int irq_remapping_supported(void)