mac80211: TDLS: deny ch-switch req on disallowed channels

If a TDLS station is not allowed to beacon on a channel, don't accept
a channel switch request to this channel.
Move channel building code up to avoid lockdep violations - reg_can_beacon
needs to take the wdev lock.

Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>