[ARM] SMDK6410: Request GPIOs for LCD power control

Going forward gpio_request() will be a requirement for GPIO API users so
call it for the LCD power GPIOs. With present code the kernel functions
but generaets loud WARN_ON()s when using the unrequested GPIOs.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>