media: sun6i-csi: Allow the video device to be open multiple times

Previously it was possible, but a recent fix for uninitialized
`ret` variable broke this behavior.

v4l2_fh_is_singular_file() check is there just to determine
whether the power needs to be enabled, and it's not a failure
if it returns false.

Fixes: ba9139116b ("media: sun6i-csi: add a missing return code")
Signed-off-by: Ondrej Jirman <megous@megous.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/sunxi/sun6i-csi/sun6i_video.c

@@ -467,7 +467,7 @@ static const struct v4l2_ioctl_ops sun6i_video_ioctl_ops = {
 static int sun6i_video_open(struct file *file)
 {
 	struct sun6i_video *video = video_drvdata(file);
-	int ret;
+	int ret = 0;
 
 	if (mutex_lock_interruptible(&video->lock))
 		return -ERESTARTSYS;
@@ -481,10 +481,8 @@ static int sun6i_video_open(struct file *file)
 		goto fh_release;
 
 	/* check if already powered */
-	if (!v4l2_fh_is_singular_file(file)) {
-		ret = -EBUSY;
+	if (!v4l2_fh_is_singular_file(file))
 		goto unlock;
-	}
 
 	ret = sun6i_csi_set_power(video->csi, true);
 	if (ret < 0)