net: ag71xx: use phylink_mii_ioctl

f1294617 removed the custom function for
ndo_eth_ioctl and used the standard phy_do_ioctl which calls
phy_mii_ioctl. However since then, this driver was ported to phylink
where it makes more sense to call phylink_mii_ioctl.

Bring back custom function that calls phylink_mii_ioctl.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240807215834.33980-1-rosenp@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>