ixgbe: query assignment of VF queues

ixgbe: query assignment of VF queues

Physical Function assignes Tx/Rx queues to each Virtual Function
according to different schemes[1]. By querying through mailbox,
VF is able to get number of Tx/Rx queues assigned to it.

Note that current Intel ixgbe driver ixgbe-3.18.7 does not fully
support mailbox message IXGBE_VF_GET_QUEUES. The service routine
for IXGBE_VF_GET_QUEUES must be fixed, otherwise PF always return
1 as Tx/Rx queue number.

[1] See section 7.2.1.2.1, 7.1.2.2 and 7.10.2.7.2 of Intel 82599 10
    Gbe Controller Datasheet.

Signed-off-by: Qinglai Xiao <jigsaw@gmail.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>