net: 802: remove dead leftover after ipx driver removal

Commit 7a2e838d ("staging: ipx: delete it from the tree") removes the
ipx driver and the config IPX. Since then, there is some dead leftover in
./net/802/, that was once used by the IPX driver, but has no other user.

Remove this dead leftover.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>