[][Add dts files for Panther RFBs with 2.5G WAN port]

[Description]
Add dts files for Panther RFBs with 2.5G WAN port, and keep other RFBs
using switch port4 as WAN port.

[Release-log]
N/A

Change-Id: Ie9703fbbead0e08b148b634b026b17ef4995e850
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4688543
7 files changed