samples: shields: x_nucleo_iks01a2: Depend on arduino_gpio

There are build issues with this sample now that it requires that the
board dts have an arduino_header node.  Add depends_on: arduino_gpio
to sample.yaml so we only build this if the board has that header.

Also remove a duplicate line for excluding the disco_l475_iot1 platform.

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