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: NRickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Reviewed-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: NDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>