i40evf: Refactor VF RSS code

Refactor VF RSS code to allow RSS on a single queue and eliminate
the need for the next_queue function.

Change-ID: I9253bad96b7f542ee7036e15636db0e5d58d8ef2
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>