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: NAkira 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: Nkernel 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: NBagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/abcaa4f5-7a9b-56b5-c11a-a88fef9d1e0a@gmail.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/ABI/testing/sysfs-bus-iio-sx9324

@@ -5,6 +5,7 @@ Contact:	Gwendal Grignou <gwendal@chromium.org>
 Description:
 		SX9324 has 3 inputs, CS0, CS1 and CS2. Hardware layout
 		defines if the input is
+
 		+ not connected (HZ),
 		+ grounded (GD),
 		+ connected to an antenna where it can act as a base