mac80211: Allow scanning on existing channel-type.

Previous code set the channel type to NO_HT, but it
appears that NO_HT packets can be sent on any channel
type, so we do not need to change the channel type
as long as the channel is correct.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>