wifi: ath9k: fix repeated to words in a comment

Delete the redundant word 'to'.
Signed-off-by: Jilin Yuan <yuanjilin@cdjrlc.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220915030559.42371-1-yuanjilin@cdjrlc.com

drivers/net/wireless/ath/ath9k/hw.h

@@ -710,7 +710,7 @@ struct ath_spec_scan {
 /**
  * struct ath_hw_ops - callbacks used by hardware code and driver code
  *
- * This structure contains callbacks designed to to be used internally by
+ * This structure contains callbacks designed to be used internally by
  * hardware code and also by the lower level driver.
  *
  * @config_pci_powersave: