iio: Add channel type for attention

Add a new channel type representing if the user's attention state to the
the system. This usually means if the user is looking at the screen or
not.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://patch.msgid.link/20241101-hpd-v3-3-e9c80b7c7164@chromium.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

include/uapi/linux/iio/types.h

@@ -51,6 +51,7 @@ enum iio_chan_type {
 	IIO_DELTA_VELOCITY,
 	IIO_COLORTEMP,
 	IIO_CHROMATICITY,
+	IIO_ATTENTION,
 };
 
 enum iio_modifier {