ath79: Fix PHY access over ag71xx driver

ath79: Fix PHY access over ag71xx driver

.ndo_do_ioctl is not called any more. For PHY MII ioctl handling, the
kernel calls .ndo_eth_ioctl now.

The SIOCSIFHWADDR and SIOCGIFHWADDR operation are handled in the generic
code in the same way just with more input validation.

See upstream Linux kernel commit:
https://git.kernel.org/linus/a76053707dbf0dc020a73b4d90cd952409ef3691

Reported-by: Cthulhu88 in https://forum.openwrt.org/t/ethernet-leds-control-for-tp-link-tl-wr1043nd-v2-v3/202378
Link: https://github.com/openwrt/openwrt/pull/16005
(cherry picked from commit f86273e742b9f01565018494733d38438e7f0098)
Link: https://github.com/openwrt/openwrt/pull/16023
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>