board: siemens: iot2050: use the named gpio to control the user-button

User-button is controlled by the mcu domain gpio number 25.
But main0 main1 mcu domain all have gpio number 25.

To identify where the gpio is from, Using gpio controll base as the prefix
to indicate the gpio resource.

Signed-off-by: chao zeng <chao.zeng@siemens.com>
Reviewed-by: Simon Glass <sjg@chromium.org>