iio: health: add MAX30102 oximeter driver support

MAX30102 is an heart rate and pulse oximeter sensor that works using
two LEDS of different wavelengths, and detecting the light reflected
back.

This patchset adds support for both IR and RED LED channels which can
be processed in userspace to determine heart rate and blood oxygen
levels. The MAX30102 part isn't completely register and functional
compatible with the existing MAX30100 driver.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>