ath5k: fix hardware queue index assignment

Like with ath9k, ath5k queues also need to be ordered by priority.
queue_info->tqi_subtype already contains the correct index, so use it
instead of relying on the order of ath5k_hw_setup_tx_queue calls.

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