Handle queue start/stop properly by maintaining
a counter to check if the pending frame count has
exceeded the threshold. Otherwise, packets would be
dropped needlessly. While at it, use a simple flag
to track queue status and use helper functions too.
Signed-off-by: NSujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>