[][Kernel][mt7988][eth][Add clock enable flow for Ethernet/Thermal]

[Description]
Add clock enabling flow for Ethernet and Thermal drivers.
Meanwhile, "always on" clock is removed from clkitg.dtsi

If without this patch, Ethernet/Thermal driver can only
use dummy clock but not actual clock preparation flow.

[Release-log]
N/A


Change-Id: I3769beab4e3087fe83636bf370bea9d33868c5b6
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6801479
4 files changed