staging:iio:adc:ad7192 scrap read from buffer for sysfs access.

No known use case and complicates in kernel interface work.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>