net/mlx4_en: Change default QoS settings

Change the default mapping between TC and TCG as follows:

Prio     |             TC/TCG
         |      from             to
         |    (set by FW)      (set by SW)
---------+-----------------------------------
0        |      0/0              0/7
1        |      1/0              0/6
2        |      2/0              0/5
3        |      3/0              0/4
4        |      4/0              0/3
5        |      5/0              0/2
6        |      6/0              0/1
7        |      7/0              0/0

These new settings cause that a pause frame for any prio stops
traffic for all prios.

Fixes: 564c274c

 ("net/mlx4_en: DCB QoS support")
Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>