ath9k_htc: Fix a compilation warning.

Initialize caldata to avoid compilation warning.

CC [M]  drivers/net/wireless/ath/ath9k/htc_drv_main.o
drivers/net/wireless/ath/ath9k/htc_drv_main.c: In function ‘ath9k_htc_config’:
drivers/net/wireless/ath/ath9k/htc_drv_main.c:172: warning: ‘caldata’ may be used uninitialized in this function
drivers/net/wireless/ath/ath9k/htc_drv_main.c:172: note: ‘caldata’ was declared here

Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -169,7 +169,7 @@ static int ath9k_htc_set_channel(struct ath9k_htc_priv *priv,
 	struct ieee80211_conf *conf = &common->hw->conf;
 	bool fastcc;
 	struct ieee80211_channel *channel = hw->conf.channel;
-	struct ath9k_hw_cal_data *caldata;
+	struct ath9k_hw_cal_data *caldata = NULL;
 	enum htc_phymode mode;
 	__be16 htc_mode;
 	u8 cmd_rsp;