[][MAC80211][mt76][add spatial extension index support]

[Description]
Add spatial extension index support.

[Release-log]
N/A

Change-Id: I6d83c6ed6ebd64bb31be308d69364183e840ffb0
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6241524
1 file changed