iio: light: al3010: Implement regmap support

Modernize and clean up the driver using the regmap framework.

With the regmap implementation, the compiler produces
a significantly smaller module.

Size before: 72 kB
Size after:  58 kB

Signed-off-by: David Heidelberg <david@ixit.cz>
Link: https://patch.msgid.link/20250402-al3010-iio-regmap-v4-4-d189bea87261@ixit.cz


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