Staging: IIO: max1363 ADC driver

Core support for MAX1361, MAX1362, MAX1363, MAX1364,
MAX1136, MAX1137, MAX1138, MAX1139, MAX1236, MAX1237,
MAX1238, MAX1239.

Ring buffer support later in series.

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