Add support for receive side scaling stride, RSSS, in mlx5en(4).

Add support for receive side scaling stride, RSSS, in mlx5en(4).

The receive side scaling stride parameter is a value which define the interval
between active receive side queues. The traffic for the inactive queues is
redirected to the nearest active queue by use of modulus. The default value
of this parameter is one, which means all receive side queues are used.

The point of this feature is to redirect more traffic to fewer receive side
queues in order to take more advantage of sorted large receive offload,
sorted LRO. The sorted LRO works better when more packets are accumulated
per service interval.

MFC after:		3 days
Approved by:		re (marius)
Sponsored by:		Mellanox Technologies