Support presence of more than just one accelerometer

Created by: fkroener

My convertible (MEDION E2228T) has two accelerometer sensors built-in.

One in the display the other in the keyboard section. They have a KIOX000A-chip and turn up with two IDs: KIOX010A and KIOX020A. Having both of them enabled in the kernel results in iio-sensor-proxy only selecting the KIOX020A one, which is unfortunately the keyboard part.

I'm not sure whether this sort of implementation is going to become more frequent. But'd be nice if iio-sensor-proxy would learn new events to turn off the keyboard (especially when turning the convertible in a way the keyboard part faces downwards, while the display doesn't rotate) - so far I just disable the keyboard / touchpad whenever the screen is rotated. But having that independent from eachother and dependent on positioning of both sensors to eachother would be nice.

Since my device lacks a LID switch this could be used as well to determine when to suspend.