RDMA/irdma: Register auxiliary driver and implement private channel OPs

RDMA/irdma: Register auxiliary driver and implement private channel OPs

Register auxiliary drivers which can attach to auxiliary RDMA
devices from Intel PCI netdev drivers i40e and ice. Implement the private
channel ops, and register net notifiers.

Link: https://lore.kernel.org/r/20210602205138.889-2-shiraz.saleem@intel.com
[flexible array transformation]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>