ath9k_htc: Use macro for caldata array size

The calibration data variable size is based on the number of
channels available in the ath9k driver.
Signed-off-by: Mohammed Shafi Shajakhan <mshajakhan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -368,7 +368,7 @@ struct ath9k_htc_priv {
 	u16 seq_no;
 	u32 bmiss_cnt;
 
-	struct ath9k_hw_cal_data caldata[38];
+	struct ath9k_hw_cal_data caldata[ATH9K_NUM_CHANNELS];
 
 	spinlock_t beacon_lock;