Create two new files fw_qos.h and fw_qos.c in mlx4_core module.

It gathers all relevant QoS firmware related commands etc, thus improving
encapsulation of the mlx4_core module. For now it contains the QoS existing
commands: mlx4_SET_PORT_SCHEDULER and mlx4_SET_PORT_PRIO2TC.
Signed-off-by: NIdo Shamay <idos@mellanox.com>
Signed-off-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>