This patch adds the rx functions for the dummy netdev:
- Functions to allocate/free the dummy netdev.
- Functions to allocate/free receiving contexts for the netdev.
- Functions to initialize/de-initialize the receive queue.
- Functions to enable/disable the receive queue.

Link: https://lore.kernel.org/r/20200511160643.173205.75087.stgit@awfm-01.aw.intel.comReviewed-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: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>