[PARISC] include <linux/prefetch.h> in drivers/parisc/iommu-helpers.h

drivers/parisc/iommu-helpers.h:62: error: implicit declaration of function 'prefetchw'
make[3]: *** [drivers/parisc/sba_iommu.o] Error 1

drivers/parisc/iommu-helpers.h needs to #include <linux/prefetch.h>
where prefetchw is declared.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/parisc/iommu-helpers.h b/drivers/parisc/iommu-helpers.h
index a9c46cc..8c33491 100644
--- a/drivers/parisc/iommu-helpers.h
+++ b/drivers/parisc/iommu-helpers.h
@@ -1,3 +1,5 @@
+#include <linux/prefetch.h>
+
 /**
  * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
  * @ioc: The I/O Controller.