iio: chemical: atlas-ph-sensor: switch to REGCACHE_NONE regmap tree

Since there are overlapping volatile regions between parts, and only
register that isn't volatile is the temperature compensation provided
from userspace.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
1 file changed