iommu/vt-d: Copy IR table from old kernel when in kdump mode

When we are booting into a kdump kernel and find IR enabled,
copy over the contents of the previous IR table so that
spurious interrupts will not be target aborted.

Tested-by: ZhenHua Li <zhen-hual@hp.com>
Tested-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index b85b81a..9e14edc 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -296,6 +296,7 @@
 /* 1MB - maximum possible interrupt remapping table size */
 #define INTR_REMAP_PAGE_ORDER	8
 #define INTR_REMAP_TABLE_REG_SIZE	0xf
+#define INTR_REMAP_TABLE_REG_SIZE_MASK  0xf
 
 #define INTR_REMAP_TABLE_ENTRIES	65536