wl12xx: fix a memory leak of probereq template upon recovery

wlvif->probereq is zeroed when adding an interface but
the skb pointed to isn't freed when the interface is removed.
This would lead to a mem leak on every recovery.
Fix it by freeing the skb when removing the interface.
Signed-off-by: Eyal Shapira <eyal@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/wl12xx/main.c

@@ -2358,6 +2358,8 @@ static void __wl1271_op_remove_interface(struct wl1271 *wl,
 		wl1271_free_ap_keys(wl, wlvif);
 	}
 
+	dev_kfree_skb(wlvif->probereq);
+	wlvif->probereq = NULL;
 	wl12xx_tx_reset_wlvif(wl, wlvif);
 	if (wl->last_wlvif == wlvif)
 		wl->last_wlvif = NULL;