IB/hfi1: Set hdr_type when tx req is allocated

Setting the protocol type should be part of initializing the tx request.
For UC and RC, the current protocol type is part of the qp priv structure.
For ud requests, it needs to be adjusted dynamically, based on the AV
posted with the WQE. This patch will simplify the initialization of the
tx request.

Fixes: 5b6cabb0 ("IB/hfi1: Add 16B RC/UC support")
Reviewed-by: Don Hiatt <don.hiatt@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>