mlx4_en: Fix QP number calculation according to module param

mlx4_en: Fix QP number calculation according to module param

commit 999bb4b3831abd6ad53023a0b8e5d304875927dd
Author: Alexander Guller <alexg@mellanox.com>
Date:   Sun Oct 9 05:29:26 2011 +0000

    mlx4_en: Fix QP number calculation according to module param

    Number of bits taken from mac table index in QP
    calculation should be based on log_num_mac parameter.

    Signed-off-by: Alexander Guller <alexg@mellanox.co.il>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Joe Jin <joe.jin@oracle.com>