RDMA/cxgb3: Set the max_mr_size device attribute correctly

cxgb3 only supports 4GB memory regions.  The lustre RDMA code uses
this attribute and currently has to code around our bad setting.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/cxgb3/iwch.h b/drivers/infiniband/hw/cxgb3/iwch.h
index 9ad9b1e..d2409a5 100644
--- a/drivers/infiniband/hw/cxgb3/iwch.h
+++ b/drivers/infiniband/hw/cxgb3/iwch.h
@@ -66,6 +66,7 @@
 	 * size (4k)^i.  Phys block list mode unsupported.
 	 */
 	u32 mem_pgsizes_bitmask;
+	u64 max_mr_size;
 	u8 can_resize_wq;
 
 	/*