bluetooth: hci_ldisc: fix deadlock condition

commit da64c27d upstream.

LDISCs shouldn't call tty->ops->write() from within
->write_wakeup().

->write_wakeup() is called with port lock taken and
IRQs disabled, tty->ops->write() will try to acquire
the same port lock and we will deadlock.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Reported-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Tested-by: Andreas Bießmann <andreas@biessmann.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[tim.niemeyer@corscience.de: rebased on 3.4.103]
Signed-off-by: Tim Niemeyer <tim.niemeyer@corscience.de>
Signed-off-by: Zefan Li <lizefan@huawei.com>