IB/hfi1: Fix trace of atomic ack

The length is incorrect, causing the trace data to
be truncated.

Add the additional 8 bytes that should have been there.
Also trace out the atomic ack in hex to aid debugging.

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