staging: iio: adis16350 and similar IMU driver

This version has the right part number in the commit message.
Whilst technically the part I listed last time is also supported
by the driver, the commit message might have caused confusion.

Another driver from Barry at Analog.  Again, I've lifted
if from the blackfin tree and done the usual sparse
and checkpatch fixes + the abi changes.  I actually
have one of these, so am particularly pleased to see
it supported!

Signed-off-by: Barry Song <Barry.Song@analog.com>
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>