iio: ABI: sysfs-bus-iio: fix a typo

Descrption -> Description

This causes some errors when parsed via scripts/get_abi.pl.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/fa90a2deebac80da42b1ad4cf570c4ace436577d.1621944866.git.mchehab+huawei@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>