iio: proximity: sx9324: add empty line in front of bullet list

"make htmldocs" emits a warning of:

    Documentation/ABI/testing/sysfs-bus-iio-sx9324:2: WARNING: Unexpected indentation.

This is due to a missing empty line in front of the bullet list.
Fix it.

Note: The line count of 2 in the warning is not exact in this case.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Fixes: 4c18a890

 ("iio:proximity:sx9324: Add SX9324 support")
Link: https://lore.kernel.org/r/202207021703.lEW6FLT1-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/abcaa4f5-7a9b-56b5-c11a-a88fef9d1e0a@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>