net/mlx4: Add mlx4_ALLOCATE_VPP implementation

Implements device ALLOCATE_VPP command, to be used for granular QoS
configuration of VFs by the PF device. Defines and queries the amount
of VPPs assigned to each port, and the amount of VPPs assigned to each
priority of each port. Once the total VPPs are split between the priorities
of a port, they may be assigned with a share of the BW or a rate limit.

Split into two functions (get/set) whoch are supplied with
mlx4_alloc_vpp_context and physical port number.

Signed-off-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>