Add another RSS method to query the indirection table entries.

There's 128 indirection table entries which correspond to the
low 7 bits of the 32 bit RSS hash.  Each value will correspond
to an RSS bucket.  (Then each RSS bucket currently will map
to a CPU.)

This is a more explicit way of figuring out which RSS bucket
is in each RSS indirection slot.  It can be inferred by the other
methods but I'd rather drivers use something more simplified and
explicit.