mac80211: assign VLAN channel contexts

Make AP_VLAN type interfaces track the AP master channel
context so they have one assigned for the various lookups.
Don't give them their own refcount etc. since they're just
slaves to the AP master.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --cc net/mac80211/chan.c
Simple merge

diff --cc net/mac80211/ieee80211_i.h
Simple merge

diff --cc net/mac80211/iface.c
Simple merge