[][dts: mt7986: Fix web upgrade failure]

[Description]
Fix web upgrade failure. Align dts compatible string and SUPPORTED
devices in image makefile.

[Release-log]
N/A

Change-Id: Iff4802061dc3f281bdf9729fc9dddcfac1500e14
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5869583
3 files changed