TXQ_FLAG_TXOKINT_ENABLE and TXQ_FLAG_TXERRINT_ENABLE are always set and
used together, and they share the same bitmask in enum ath9k_tx_queue_flags.
Simplify the code that tests for these flags.
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>