ath9k: Fix some smatch warnings

drivers/net/wireless/ath/ath9k/hif_usb.c +135 hif_usb_mgmt_cb(6) warn:
variable dereferenced before check 'cmd'
drivers/net/wireless/ath/ath9k/btcoex.c +77 ath9k_hw_init_btcoex_hw(38)
error: buffer overflow 'ah->hw_gen_timers.gen_timer_index' 32 <=
2009813776

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 1d11ae1..d3f4a59c 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -130,12 +130,14 @@
 static void hif_usb_mgmt_cb(struct urb *urb)
 {
 	struct cmd_buf *cmd = (struct cmd_buf *)urb->context;
-	struct hif_device_usb *hif_dev = cmd->hif_dev;
+	struct hif_device_usb *hif_dev;
 	bool txok = true;
 
 	if (!cmd || !cmd->skb || !cmd->hif_dev)
 		return;
 
+	hif_dev = cmd->hif_dev;
+
 	switch (urb->status) {
 	case 0:
 		break;