IB/mlx4: Don't overwrite fast registration page list when posting work request

The low-level mlx4 driver modified the page-list addresses for fast
register work requests post send to big-endian, and set a "present"
bit.  This caused problems later when the consumer attempted to unmap
the pages using the page-list (using the list addresses which were
assumed to be still in CPU-endian order).  Fix the mlx4 driver to
allocate two buffers and use a private buffer for the hardware-format
bus addresses.

This patch fixes <https://bugs.openfabrics.org/show_bug.cgi?id=1571>,
an NFS/RDMA server crash.  The cause of the crash was found by Vu Pham
of Mellanox.  The fix is along the lines suggested by Steve Wise in
comment #21 in bug 1571.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/mlx4/mlx4_ib.h b/drivers/infiniband/hw/mlx4/mlx4_ib.h
index 9974e88..8a7dd67 100644
--- a/drivers/infiniband/hw/mlx4/mlx4_ib.h
+++ b/drivers/infiniband/hw/mlx4/mlx4_ib.h
@@ -86,6 +86,7 @@
 
 struct mlx4_ib_fast_reg_page_list {
 	struct ib_fast_reg_page_list	ibfrpl;
+	__be64			       *mapped_page_list;
 	dma_addr_t			map;
 };