gpio: xra1403: remove unneeded spi_set_drvdata()

There is no matching spi_get_drvdata() call in the driver, so there is no
need to do spi_set_drvdata(). This looks like it probably was copied from a
driver that used both spi_set_drvdata() & spi_get_drvdata().

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>