net: phy: Add the Airoha EN8811H PHY driver

net: phy: Add the Airoha EN8811H PHY driver

Add the driver for the Airoha EN8811H 2.5 Gigabit PHY. The PHY supports
100/1000/2500 Mbps with auto negotiation only.

The driver uses two firmware files, for which updated versions are added to
linux-firmware already.

Locating the AIROHA FW within the filesystem at the designated partition
and path will trigger its automatic loading and writing to the PHY via MDIO.
If need board specific loading override,
please override the en8811h_read_fw function on board or architecture level.

Based on the Linux upstream AIROHA EN8811H driver code(air_en8811h.c),
I have modified the relevant process to align with the U-Boot boot sequence.
and have validated this on Banana Pi BPI-R3 Mini.

Signed-off-by: Lucien.Jheng <lucienzx159@gmail.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>