IB/hfi1: Combine shift copy and byte copy for SGE reads

Prevent over-reading the SGE length by using byte
reads for non quad-word reads.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>