ath9k: fix retry counting / BAR handling during queue flush

When tx is suspended temporarily and the queue is flushed, do not increase
the retry count or attempt to send out BAR frames. Instead simply retry
the affected subframes normally after the reset.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>