realtek: 6.12: refactor EEE for RTL8218B/D and RTL8214FC

realtek: 6.12: refactor EEE for RTL8218B/D and RTL8214FC

Three different code paths for the same phy model. Now the bus
is prepared to handle c45 (mmd) read/writes correctly. Remove
the custom implementations and let generic kernel functions do
their best. To achieve this

- disable the PHY-mode EEE in rtl821x_config_init() as upstream does
- provide mmd read/write functions that avoid EEE via c45 over c22

While chaning the phy_driver functions sort them alphabetically.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/18935
Signed-off-by: Robert Marko <robimarko@gmail.com>