[media] s5p-fimc: Fix compiler warning in fimc-lite.c

This patch is an update to changed media_entity_pipeline_start()
signature in commit af88be38,
"media: Add link_validate() op to check links to the sink pad"

It fixes the following warning:

drivers/media/video/s5p-fimc/fimc-lite.c: In function ‘fimc_lite_streamon’:
drivers/media/video/s5p-fimc/fimc-lite.c:765:29: warning: ignoring return value
of ‘media_entity_pipeline_start’, declared with attribute warn_unused_result [-Wunused-result]
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/s5p-fimc/fimc-lite.c

@@ -764,7 +764,9 @@ static int fimc_lite_streamon(struct file *file, void *priv,
 	if (fimc_lite_active(fimc))
 		return -EBUSY;
 
-	media_entity_pipeline_start(&sensor->entity, p->m_pipeline);
+	ret = media_entity_pipeline_start(&sensor->entity, p->m_pipeline);
+	if (ret < 0)
+		return ret;
 
 	ret = fimc_pipeline_validate(fimc);
 	if (ret) {