staging:iio:accel:adis16204: use peak_raw info_mask element + push some defs down from header.

Currently this is the only driver using some of the defines in accel.h.
If these become common we'll just add them to the channel_spec options,
for now push down into this driver.

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>