mlx4_en: Using blue flame support

Doorbell is used according to usage of BlueFlame.
For Blue Flame to work in Ethernet mode QP number should have 0
at bits 6,7.
Allocating range of QPs accordingly.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>