iommu/amd: Add slab-cache for irq remapping tables

The irq remapping tables for the AMD IOMMU need to be
aligned on a 128 byte boundary. Create a seperate slab-cache
to guarantee this alignment.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 6f51483..b6a8079 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -95,6 +95,8 @@
 	u32 data[4];
 };
 
+struct kmem_cache *amd_iommu_irq_cache;
+
 static void update_domain(struct protection_domain *domain);
 static int __init alloc_passthrough_domain(void);