linux-wandboard

tty: note race we need to fix

This was identified by Vincent Pillet with a high speed interface that uses
low latency mode. In the low latency case we have a tiny race but it can
be hit.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>