iio:adc:ad799x: Add helper function to read/write config register

16-bit on ad7997/ad7998, 8-bit elsewhere

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