alpha: sg_virt() fallout

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index ee07dce..2d00a08 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -7,6 +7,7 @@
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/bootmem.h>
+#include <linux/scatterlist.h>
 #include <linux/log2.h>
 
 #include <asm/io.h>