IB/hfi1: Fix ordering of trace for accuracy

The postitioning of the sdma ibhdr trace was
causing an extra trace message when the tx send
returned -EBUSY.

Move the trace to just before the return
and handle negative return values to avoid
any trace.

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