mlxsw: Use correct skb length when dumping payload

Do not use the length of the transmitted skb (which was freed), but
that of the response skb.

This issue was discovered using the Kernel Address sanitizer (KASan).
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core.c

@@ -1073,7 +1073,7 @@ static int mlxsw_core_reg_access_emad(struct mlxsw_core *mlxsw_core,
 			mlxsw_core->emad.tid - 1);
 		mlxsw_core_buf_dump_dbg(mlxsw_core,
 					mlxsw_core->emad.resp_skb->data,
-					skb->len);
+					mlxsw_core->emad.resp_skb->len);
 
 		dev_kfree_skb(mlxsw_core->emad.resp_skb);
 	}