Input: soc_button_array - use platform_device_register_resndata()

The registration of gpio-keys device can be written much shorter
by using the platform_device_register_resndata() helper.

Signed-off-by: Enrico Weigelt <info@metux.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>