[][Refactor mt7981 eth clk to real clk source from clk driver]

[Description]
Refactor mt7981 eth clk to real clk source from clk driver

[Release-log]
N/A

Change-Id: I09cfe5db8b19cf7c074b72effdc2b584984e7307
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5325658
3 files changed