The push feature does not work as expected in x722 and has historically
been disabled in the driver.

Purge all remaining code related to the push feature in i40iw.

Link: https://lore.kernel.org/r/20201125005616.1800-3-shiraz.saleem@intel.comSigned-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>