media: s5k4ecgx: Switch to GPIO descriptors

The driver has an option to pass in GPIO numbers from platform
data but this is not used in the kernel so delete this and the
whole platform data mechanism.

Get GPIO descriptors using the standard API and simplify the code,
gpiolib will handle any inversions.

Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai@amarulasolutions.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>