staging: panel: Move LCD-related state into struct lcd

Move more or less all LCD-related state into struct lcd
in order to get better cohesion; use bool instead of int
where it makes sense.

Signed-off-by: Mariusz Gorski <marius.gorski@gmail.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>