This fixes this sparse complaint:

  CHECK   drivers/net/wireless/ath/ath9k/htc_drv_main.c
drivers/net/wireless/ath/ath9k/htc_drv_main.c:441:5:
	warning: symbol 'ath9k_htc_tx_aggr_oper'
		 was not declared. Should it be static?
Signed-off-by: NLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>