iio: addac: ad74xxx: Constify struct iio_chan_spec​
'struct iio_chan_spec' are not modified in these drivers.
Constifying this structure moves some data to a read-only section, so
increase overall security.
On a x86_64, with allmodconfig:
Before:
======
text data bss dec hex filename
35749 5879 384 42012 a41c drivers/iio/addac/
ad74115.o
32242 3297 384 35923 8c53 drivers/iio/addac/ad74413r.o
After:
=====
text data bss dec hex filename
39109 2519 384 42012 a41c drivers/iio/addac/
ad74115.o
33842 1697 384 35923 8c53 drivers/iio/addac/ad74413r.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://patch.msgid.link/da291278e78b983ea2e657a25769f7d82ea2a6d0.1725717045.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>