iio: hid-sensors-prox: Make proximity channel indexed

We are going to introduce more proximity channels. Make proximity a
indexed channel now, in a simple patch, so the change can be easily
bisected if there are any issues.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://patch.msgid.link/20241101-hpd-v3-4-e9c80b7c7164@chromium.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/hid-sensor-prox.c

@@ -40,6 +40,7 @@ static const struct iio_chan_spec prox_channels[] = {
 		BIT(IIO_CHAN_INFO_SAMP_FREQ) |
 		BIT(IIO_CHAN_INFO_HYSTERESIS),
 		.scan_index = CHANNEL_SCAN_INDEX_PRESENCE,
+		.indexed = true,
 	}
 };