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>

drivers/net/ethernet/mellanox/mlx4/mr.c

@@ -816,6 +816,9 @@ int mlx4_fmr_alloc(struct mlx4_dev *dev, u32 pd, u32 access, int max_pages,
 	u64 mtt_offset;
 	int err = -ENOMEM;
 
+	if (max_maps > dev->caps.max_fmr_maps)
+		return -EINVAL;
+
 	if (page_shift < (ffs(dev->caps.page_size_cap) - 1) || page_shift >= 32)
 		return -EINVAL;