mlx4: Enforce device max FMR maps in FMR alloc

ConnectX devices have a limit on the number of mappings that can be
done on an FMR before having to call sync_tpt.  The current
mlx4_ib driver reports the limit correctly in max_map_per_fmr in
.query_device(), but mlx4_core doesn't check it when actually
allocating FMRs.

Add a max_fmr_maps field to struct mlx4_caps and enforce this maximum
value on FMR allocations.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index aea6190..263d2ae 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -273,6 +273,7 @@
 	int			num_comp_vectors;
 	int			comp_pool;
 	int			num_mpts;
+	int			max_fmr_maps;
 	int			num_mtts;
 	int			fmr_reserved_mtts;
 	int			reserved_mtts;