media: am437x-vpfe: Setting STD to current value is not an error

VIDIOC_S_STD should not return an error if the value is identical
to the current one.
This error was highlighted by the v4l2-compliance test.
Signed-off-by: Benoit Parrot <bparrot@ti.com>
Acked-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/am437x/am437x-vpfe.c

@@ -1822,6 +1822,10 @@ static int vpfe_s_std(struct file *file, void *priv, v4l2_std_id std_id)
 	if (!(sdinfo->inputs[0].capabilities & V4L2_IN_CAP_STD))
 		return -ENODATA;
 
+	/* if trying to set the same std then nothing to do */
+	if (vpfe_standards[vpfe->std_index].std_id == std_id)
+		return 0;
+
 	/* If streaming is started, return error */
 	if (vb2_is_busy(&vpfe->buffer_queue)) {
 		vpfe_err(vpfe, "%s device busy\n", __func__);