iwlagn: update rate scaling with BA notifications

In the current code, the rate scaling isn't fed with
statistics from the BA notifications.

This is since my patch:

	iwlagn: reclaim the packets in transport layer

Fix that.

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>