Input: pmic8xxx-keypad - fix build by removing gpio configuration

The gpio configuration in this driver doesn't work because the
gpio.h include doesn't exist. Remove the configuration as it
isn't strictly necessary, allowing us to actually compile this
driver. If it's needed in the future, it should be done via a
pinctrl driver.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>