staging:iio:gyro:adis16060 convert to iio_chan_spec

Still a very odd driver. This patch has the side effect of changing
it's name slightly.

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