iio: proximity: sx9500: Assign interrupt from GpioIo()

iio: proximity: sx9500: Assign interrupt from GpioIo()

The commit 8a1539e452a3

("iio: remove gpio interrupt probing from drivers that use a single interrupt")

removed custom IRQ assignment for the drivers which are enumerated via
ACPI or OF. Unfortunately, some ACPI tables have IRQ line defined as
GpioIo() resource and thus automatic IRQ allocation will fail.

Partially revert the commit 8a1539e452a3 to restore original behaviour.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>