mediatek: filogic: adapt BananaPi-R4 for use with upstream DT

mediatek: filogic: adapt BananaPi-R4 for use with upstream DT

 * the variant with 2.5G PHY instead of LAN SFP is called '2p5'
   upstream and 'poe' in our downstream Linux 6.6 DT. Use the right
   DTS depending on the kernel version and set an additional
   compatible.

 * drop additional DT overlay for WiFi.
   The final version of the board uses a physical switch for the 12V
   power of the WiFi module and the I2C EEPROM of the module always
   comes empty (instead of with a MAC address).

Signed-off-by: Daniel Golle <[email protected]>