samples: shields: x_nucleo_iks01a3: rename arduino_header depend

Change arduino_header depend to arduino_gpio as that is more meaningful.
Its easy to mistake arduino_header to mean the board has an arduino
header in general.  What we want to depend on is that we have the gpio
connector in the dts that has 'arduino_header' as the node label.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>