IB/hfi1: Mask out A bit from psn trace

The trace logic prior to the fixes below used to mask the
A bit from the psn. It now mistakenly displays the A bit,
which is already displayed separately.

Fix by adding the appropriate mask to the psn tracing.

Fixes: 228d2af1 ("IB/hfi1: Separate input/output header tracing")
Fixes: 863cf89d ("IB/hfi1: Add 16B trace support")
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Don Hiatt <don.hiatt@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>