Bluetooth: hci_uart: fix race during initialization

'hci_register_dev()' calls power up function, which is executed by
kworker - 'hci_power_on()'. This function does access to bluetooth chip
using callbacks from 'hci_ldisc.c', for example 'hci_uart_send_frame()'.
Now 'hci_uart_send_frame()' checks 'HCI_UART_PROTO_READY' bit set, and
if not - it fails. Problem is that 'HCI_UART_PROTO_READY' is set after
'hci_register_dev()', and there is tiny chance that 'hci_power_on()' will
be executed before setting this bit. In that case HCI init logic fails.

Patch moves setting of 'HCI_UART_PROTO_READY' before calling function
'hci_uart_register_dev()'.

Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

drivers/bluetooth/hci_ldisc.c

@@ -707,12 +707,13 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
 
 	hu->proto = p;
 
+	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+
 	err = hci_uart_register_dev(hu);
 	if (err) {
 		return err;
 	}
 
-	set_bit(HCI_UART_PROTO_READY, &hu->flags);
 	return 0;
 }