realtek: dts: adapt RTL8214FC bus location on RTL839x

realtek: dts: adapt RTL8214FC bus location on RTL839x

The RTL839x has the following hard-coded bus topology:
- Bus 0: Port 0-23
- Bus 1: Port 24-51

So the bus number and the PHY address in the dts are mostly
ignored. Nevertheless fix the assignment for the Zyxel GS1920.
This does not change the functionality it just describes the
hardware correctly. While we are here add the PHY package
description too.

Link: https://github.com/openwrt/openwrt/pull/24281
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>