iio: ABI: Add a new location label

Add "accel-camera" when an IMU is location near the camera in a swivel
sub-assembly. These IMU are used for AR applications.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Link: https://lore.kernel.org/r/20220427190804.961697-2-gwendal@chromium.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>