net: tn40xx: create swnode for mdio and aqr105 phy and add to mdiobus

In case of an AQR105-based device, create a software node for the mdio
function, with a child node for the Aquantia AQR105 PHY, providing a
firmware-name (and a bit more, which may be used for future checks) to
allow the PHY to load a MAC specific firmware from the file system.

The name of the PHY software node follows the naming convention suggested
in the patch for the mdiobus_scan function (in the same patch series).

Signed-off-by: Hans-Frieder Vogt <hfdevel@gmx.net>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250322-tn9510-v3a-v7-5-672a9a3d8628@gmx.net


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