ar71xx: allow unknown multicast frames to pass to the CPU on AR934x

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35564 3c298f89-4303-0410-b956-a3cf2f4a3e73
mac80211/hostapd: short_preamble is a per-vif option and should be enabled by default

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35565 3c298f89-4303-0410-b956-a3cf2f4a3e73
mac80211: add CCK rate support to minstrel_ht to improve range

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35566 3c298f89-4303-0410-b956-a3cf2f4a3e73