wl12xx: silence tx_attr uninitialized warning in wl1271_tx_fill_hdr

  CC [M]  drivers/net/wireless/wl12xx/tx.o
drivers/net/wireless/wl12xx/tx.c: In function ‘wl1271_tx_fill_hdr’:
drivers/net/wireless/wl12xx/tx.c:288:6: warning: ‘tx_attr’ may be used uninitialized in this function
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/wl12xx/tx.c

@@ -285,7 +285,7 @@ static void wl1271_tx_fill_hdr(struct wl1271 *wl, struct wl12xx_vif *wlvif,
 	struct wl1271_tx_hw_descr *desc;
 	int aligned_len, ac, rate_idx;
 	s64 hosttime;
-	u16 tx_attr;
+	u16 tx_attr = 0;
 	bool is_dummy;
 
 	desc = (struct wl1271_tx_hw_descr *) skb->data;