Minor virtio-net queues cleanup
Minor virtio-net queues cleanup

   1. the max queue size for rx and tx is now 4096 and the final value is
      not hardcoded.
   2. the receive operation now gets one buffer descriptor at a time, instead
      of two.

mato/solo5,Weichen81/solo5,mato/solo5,mato/solo5,Weichen81/solo5,djwillia/solo5,Solo5/solo5,djwillia/solo5,Solo5/solo5,djwillia/solo5,Weichen81/solo5