RDMA/hfi1: Remove all traces of diagpkt support

One of the concessions we made to get our driver upstream was to remove
the diagnostic packet support. There is however still some cruft that was
left over.  Remove it.

Link: https://lore.kernel.org/r/20220520183727.48973.93587.stgit@awfm-01.cornelisnetworks.com


Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>