IB/ipath: Translate legacy diagpkt into newer extended diagpkt

IB/ipath: Translate legacy diagpkt into newer extended diagpkt

This patch addresses an issue where the legacy diagpacket is sent in
from the user, but the driver operates on only the extended
diagpkt. This patch specifically initializes the extended diagpkt
based on the legacy packet.

Cc: <stable@vger.kernel.org>
Reported-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>