IB/ipath: Translate legacy diagpkt into newer extended diagpkt

commit 7e6d3e5c70f13874fb06e6b67696ed90ce79bd48 upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>