iio: chemical: sps30: fix attribute kernel version

4.22 have never existed and this change was actually added to 5.0
hence fix the numbering.
Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/ABI/testing/sysfs-bus-iio-sps30

 What:		/sys/bus/iio/devices/iio:deviceX/start_cleaning
 Date:		December 2018
-KernelVersion:	4.22
+KernelVersion:	5.0
 Contact:	linux-iio@vger.kernel.org
 Description:
 		Writing 1 starts sensor self cleaning. Internal fan accelerates