staging: iio: ad7476: fix !CONFIG_IIO_RING_BUFFER build issue reported by Randy Dunlap

Fix function function decalration
Enable CONFIG_IIO_RING_BUFFER for the ad7476 driver

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2 files changed