[][MAC80211][misc][sync MT7996 mp2.0 FW]

[Description]
Refactor build script to sync with internal.
Update MT7996 mp2.0 FW to 20230516

[Release-log]
N/A

Change-Id: Ia7f87f9de0984c5dd300a070066432ec7b51fb84
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7589044
9 files changed