iio: proximity: isl29501: make use of of_device_id table

Reference the of_device_id table in the driver structure, so it will be
used for module autoloading and device matching.  This fixes clang W=1
warning:

  isl29501.c:999:34: error: unused variable 'isl29501_i2c_matches' [-Werror,-Wunused-const-variable]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240225201654.49450-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>