staging/rdma/hfi1: Fix per-VL transmit discard counts

Implement per-VL transmit counters.  Not all errors can be
attributed to a particular VL, so make a best attempt.
o Extend the egress error bits used to count toward transmit
  discard.
o When an egress error or send error occur, try to map back
  to a VL.
o Implement a SDMA engine to VL (back) map.
o Add per-VL port transmit counters

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>