iio: proximity: irsd200: Drop unused include

The driver includes the legacy GPIO header <linux/gpio.h> but doesn't
use any symbols from it. Drop it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://lore.kernel.org/r/20231128-descriptors-iio-v1-1-da1e94755db6@linaro.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>