media: imx: imx7_mipi_csis: Make source .s_power() optional

The .s_power() subdev operation is optional, don't error out when the
source doesn't implement it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/imx/imx7-mipi-csis.c

@@ -627,7 +627,7 @@ static int mipi_csis_s_stream(struct v4l2_subdev *mipi_sd, int enable)
 			return ret;
 		}
 		ret = v4l2_subdev_call(state->src_sd, core, s_power, 1);
-		if (ret < 0)
+		if (ret < 0 && ret != -ENOIOCTLCMD)
 			return ret;
 	}
 
@@ -649,6 +649,8 @@ static int mipi_csis_s_stream(struct v4l2_subdev *mipi_sd, int enable)
 	} else {
 		v4l2_subdev_call(state->src_sd, video, s_stream, 0);
 		ret = v4l2_subdev_call(state->src_sd, core, s_power, 0);
+		if (ret == -ENOIOCTLCMD)
+			ret = 0;
 		mipi_csis_stop_stream(state);
 		state->flags &= ~ST_STREAMING;
 		if (state->debug)