econet: major rewrite of ethernet driver

econet: major rewrite of ethernet driver

Update the econet-eth driver to a new version which is of
sufficient quality that it is realistic to think about upstreaming.

This version is now NAPI based, collects stats, downloads without
dropped packets anymore, has debugfs introspection, and can be
unloaded and reloaded (providing the reset controller is present).

PR #21545 is recommended but not required, without this the
ethernet driver will log a warning on startup because it can't get
the resets and it will be impossible to unload and reload the
driver without a reboot. However, the PoC driver was not capable of
reloading so this is not a regression.

Signed-off-by: Caleb James DeLisle <cjd@cjdns.fr>
Link: https://github.com/openwrt/openwrt/pull/21557
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>