[][MAC80211][mt76][fix mt76 Makefile]

[Description]
Fix mt76 Makefile used for release.

[Release-log]
N/A

Change-Id: I6a57f0332f221c375de8bce332cde3492754fc4e
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6970431
1 file changed