fbdev: omapfb: panel-lgphilips-lb035q02: remove backlight GPIO handling

With f048e8c1 ("omapfb: panel-lgphilips-lb035q02: Remove legacy boot
support") it is no longer possible to specify GPIO to control the
backlight. Remove code trying to request and toggle it.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>