RDMA/qib: Use attributes for the port sysfs

qib should not be creating a mess of kobjects to attach to the port
kobject - this is all attributes. The proper API is to create an
attribute_group list and create it against the port's kobject.

Link: https://lore.kernel.org/r/911e0031e1ed495b0006e8a6efec7b67a702cd5e.1623427137.git.leonro@nvidia.com


Tested-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>