Fix an implicit declaration of function error for rpr0521 under some configs

When CONFIG_RPR0521 is enabled without CONFIG_IIO_TRIGGERED_BUFFER,
the build results in "implicit declaration of function" errors, e.g.,
  drivers/iio/light/rpr0521.c:434:3: error: implicit declaration of function
           'iio_trigger_poll_chained' [-Werror=implicit-function-declaration]
    434 |   iio_trigger_poll_chained(data->drdy_trigger0);
        |   ^~~~~~~~~~~~~~~~~~~~~~~~

This fix adds select dependencies to RPR0521's configuration declaration.

Fixes: e12ffd24 ("iio: light: rpr0521 triggered buffer")
Signed-off-by: NPaul Gazzillo <paul@pgazz.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216678Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221110214729.ls5ixav5kxpeftk7@deviceSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>