f_phonet: dev_kfree_skb instead of dev_kfree_skb_any in TX callback

Network device TX is never run in IRQ context, and skb is freed outside
of the IRQ-disabling spin lock. So checking for IRQ was a waste of time
here.
Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/usb/gadget/f_phonet.c

@@ -255,7 +255,7 @@ static int pn_net_xmit(struct sk_buff *skb, struct net_device *dev)
 	spin_unlock_irqrestore(&port->lock, flags);
 out:
 	if (unlikely(skb)) {
-		dev_kfree_skb_any(skb);
+		dev_kfree_skb(skb);
 		dev->stats.tx_dropped++;
 	}
 	return 0;