We still have some legacy code needing the callback functions
that won't work properly without platform data. To use platform
data for twl4030-gpio, we need to not trash the possible data.

Cc: linux-gpio@vger.kernel.org
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
[tony@atomide.com: folded in fix from Fengguang to use struct assignment]
Signed-off-by: NTony Lindgren <tony@atomide.com>