staging:iio:ad7291: Simplify threshold register lookup

The AD7291 register map is nicely uniform and we can easily compute the
threshold register address for a certain channel using simple math instead of
using a look-up table.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
1 file changed