staging:iio:adc:ad7606 Convert to new channel registration method Update Add missing call to iio_trigger_notify_done() Set pollfunc top and bottom half handler

V3: rebase fixup.

Backported to relevant merge point by Jonathan Cameron.
V2: IIO_CHAN macro usage update
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>