IB/hfi,rdmavt,qib,opa_vnic: Update MAINTAINERS

Intel has spun off the Omni-Path Architecture group which is now a new
company known as Cornelis Networks. Updating the MAINTAINERS file to
reflect this change and our new email addresses.

Link: https://lore.kernel.org/r/20201008171803.189100.43448.stgit@awfm-01.aw.intel.com


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