Bluetooth: hci_ll: don't call kfree_skb() under spin_lock_irqsave()

It is not allowed to call kfree_skb() from hardware interrupt
context or with interrupts being disabled. So replace kfree_skb()
with dev_kfree_skb_irq() under spin_lock_irqsave().

Fixes: 166d2f6a ("[Bluetooth] Add UART driver for Texas Instruments' BRF63xx chips")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

drivers/bluetooth/hci_ll.c

@@ -345,7 +345,7 @@ static int ll_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 	default:
 		BT_ERR("illegal hcill state: %ld (losing packet)",
 		       ll->hcill_state);
-		kfree_skb(skb);
+		dev_kfree_skb_irq(skb);
 		break;
 	}