IB/iser: Reuse ib_sg_to_pages

We have in iser iser_sg_to_page_vec which has exactly
the same role as ib_sg_to_pages. Customize the page_vec
to hold a fake MR so we can reuse ib_sg_to_pages.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/iser/iscsi_iser.h

@@ -585,9 +585,8 @@ struct iscsi_iser_task {
 
 struct iser_page_vec {
 	u64 *pages;
-	int length;
-	int offset;
-	int data_size;
+	int npages;
+	struct ib_mr fake_mr;
 };
 
 /**