ath9k_hw: remove a useless WARN_ON

&ah->curchan->ani can never be NULL

Signed-off-by: Felix Fietkau <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

drivers/net/wireless/ath/ath9k/ani.c

···
 		return;
 
 	aniState = &ah->curchan->ani;
-	if (WARN_ON(!aniState))
-		return;
-
 	if (!ath9k_hw_ani_read_counters(ah))
 		return;