iwlagn: move the stop / wake queue logic to transport layer

priv->mac80211_registered and priv->hw needed to move to shared.
stop_queue API was added in order to allow the upper layer to stop
the SW queues for regulatory purposes.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>