[][dts: mt7981: Fix web upgrade failure]

[Description]
Change supported-device names to align with compatible string in dts.
Web upgrading will check if the two strings match.

[Release-log]
N/A

Change-Id: I4680e0a945429c5d9e7e807a06a480dbe240b383
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5702933
3 files changed