linux-wandboard

tty: Avoid false-sharing flip buffer ptrs

Separate the head and tail ptrs to avoid cache-line contention
(so called 'false-sharing') between concurrent threads.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>