staging:iio:gyro: adis16060 cleanup, move to abi and bug fixes.

Moved to standard sysfs naming and got rid of direct register writing from
userspace.

The rx and tx buffers are never used together so just have one and avoid
the need to malloc it by using putting it in the state structure and
using the ____cacheline_aligned trick.

A number of obvious bugs also fixed and correction of register address
defines in header which has now been squashed into the driver.

I don't have one of these so can't test. This is done off datasheet.
Note that the driver had parts that definitely wouldn't work before
this patch.  Now it 'might' assuming I haven't messed up too badly.

I've left fixing the fact that you can only have one of these on a given
machine for another day.

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>