cfg80211: fix extension channel checks to initiate communication

When operating in a mode that initiates communication and using
HT40 we should fail if we cannot use both primary and secondary
channels to initiate communication. Our current ht40 allowmap
only covers STA mode of operation, for beaconing modes we need
a check on the fly as the mode of operation is dynamic and
there other flags other than disable which we should read
to check if we can initiate communication.

Do not allow for initiating communication if our secondary HT40
channel has is either disabled, has a passive scan flag, a
no-ibss flag or is a radar channel. Userspace now has similar
checks but this is also needed in-kernel.

Reported-by: Jouni Malinen <jouni.malinen@atheros.com>
Cc: stable@kernel.org
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>