[][Add upstream thermal driver for MT7981]

[Description]
Add upstream thermal driver for MT7981.
Currently the driver supports cross-platform thermal feature.
	- V1 : MT8173, MT8183, MT2701, MT2712
	- V2 : MT7622
	- V3 : MT7981, MT7986

If without this change, MT7981 ASIC is unable to read
ARM CPU temperature.

[How-to]
The way to show current temperature.
	- cat /sys/class/thermal/thermal_zone0/temp

[Release-log]
N/A

Change-Id: I0244bbb897fffc2f33b494ec4a8f69787a14a6e9
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5401091
diff --git a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7981-clkitg.dtsi b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7981-clkitg.dtsi
index 1a302ee..19df422 100644
--- a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7981-clkitg.dtsi
+++ b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7981-clkitg.dtsi
@@ -84,7 +84,7 @@
 			<&infracfg_ao CK_INFRA_AP_DMA_CK>,
 			<&infracfg_ao CK_INFRA_SEJ_CK>,
 			<&infracfg_ao CK_INFRA_SEJ_13M_CK>,
-			<&infracfg_ao CK_INFRA_THERM_CK>,
+			<&clk40m>,
 			<&clk40m>,
 			<&clk40m>,
 			<&clk40m>,