IB/hfi1: Activate the dummy netdev

As described in earlier patches, ipoib netdev will share receive
contexts with existing VNIC netdev through a dummy netdev. The
following changes are made to achieve that:
- Set up netdev receive contexts after user contexts. A function is
  added to count the available netdev receive contexts.
- Add functions to set/get receive map table free index.
- Rename NUM_VNIC_MAP_ENTRIES as NUM_NETDEV_MAP_ENTRIES.
- Let the dummy netdev own the receive contexts instead of VNIC.
- Allocate the dummy netdev when the hfi1 device is added and free it
  when the device is removed.
- Initialize AIP RSM rules when the IpoIb rxq is initialized and
  remove the rules when it is de-initialized.
- Convert VNIC to use the dummy netdev.

Link: https://lore.kernel.org/r/20200511160649.173205.4626.stgit@awfm-01.aw.intel.com


Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Sadanand Warrier <sadanand.warrier@intel.com>
Signed-off-by: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>