realtek: simplify RTL8214FC handling

realtek: simplify RTL8214FC handling

Now that we have a get_base_phy() function a lot code of the RTL8214FC
handling can be cleaned up. To name a few:

- use phy_read/phy_write instead of mdiobus functions or the even worse
  phy_package_..._paged() helpers
- replace messages with phydev_info()
- remove if/else statements around copper/fibre handling

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19810
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>