mac80211: process skb_queue while scanning in HW

Queued frames aren't processed during scan, which results in an inability
to complete the BA session establishment until the scan ends. Since we
can't tx frames until the BA agreement setup is complete, it might result
in a very large latency during scan.
Fix this by allowing to process queued skbs while scanning in HW. This
should be ok since the devices which support hw scan should be able
to handle tx/rx while scanning.
During SW scan, mac80211 drops any txed frames besides probes and NDPs,
so it is still needed to delay processing of the queued frames till the
SW scan is done.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>