iio: health/afe440x: Fix scan_index assignment

The LED channels are not scannable and so scan_index should
be negative, fix this here.
Signed-off-by: NAndrew F. Davis <afd@ti.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/health/afe440x.h

@@ -125,7 +125,7 @@ struct afe440x_reg_info {
 		.type = IIO_CURRENT,				\
 		.channel = _index,				\
 		.address = _index,				\
-		.scan_index = _index,				\
+		.scan_index = -1,				\
 		.extend_name = _name,				\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
 			BIT(IIO_CHAN_INFO_SCALE),		\