[][MAC80211][WiFi6][mt76][Fix muru_onoff as all enabled by default]

[Description]
Fix muru_onoff default value as 0xF, which means all MU & RU are
enabled. The purpose of this commit is to align muru_onoff value with
hostapd and mt76 driver.

[Release-log]
N/A

Change-Id: I8c150fb6cef08a7befa94ccde2dea64acfd8e596
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8382711
1 file changed