Revert "scatterlist: use sg_phys()"

commit db0fa0cb0157 "scatterlist: use sg_phys()" did replacements of
the form:

    phys_addr_t phys = page_to_phys(sg_page(s));
    phys_addr_t phys = sg_phys(s) & PAGE_MASK;

However, this breaks platforms where sizeof(phys_addr_t) >
sizeof(unsigned long).  Revert for 4.3 and 4.4 to make room for a
combined helper in 4.5.

Cc: <stable@vger.kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: db0fa0cb0157 ("scatterlist: use sg_phys()")
Suggested-by: Joerg Roedel <joro@8bytes.org>
Reported-by: Vitaly Lavrov <vel21ripn@gmail.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index abae363..0e3b009 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1430,7 +1430,7 @@
 	min_pagesz = 1 << __ffs(domain->ops->pgsize_bitmap);
 
 	for_each_sg(sg, s, nents, i) {
-		phys_addr_t phys = sg_phys(s);
+		phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;
 
 		/*
 		 * We are mapping on IOMMU page boundaries, so offset within