realtek: dts: cleanup of ethernet link speed

realtek: dts: cleanup of ethernet link speed

Realtek switches have a very simple network adapter for the SOC.
They can ship packets via DMA without further offloading features.
Even on the RTL931x devices they can barely reach 50MB/s. In the
dts there is a mix of 1G/10G definitions. To be consistent and
better reflect the performance set the link speed to 1000.
This is only cosmetic.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/22639
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>