[media] OMAP_VOUT: Change hardcoded device node number to -1

With addition of media-controller framework, now we have various
device nodes (/dev/videoX) getting created, so hardcoding
minor number in video_register_device() is not recommended.

So let V4L2 framework choose free minor number for the device.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/omap/omap_vout.c

@@ -2391,7 +2391,7 @@ static int __init omap_vout_create_video_devices(struct platform_device *pdev)
 		/* Register the Video device with V4L2
 		 */
 		vfd = vout->vfd;
-		if (video_register_device(vfd, VFL_TYPE_GRABBER, k + 1) < 0) {
+		if (video_register_device(vfd, VFL_TYPE_GRABBER, -1) < 0) {
 			dev_err(&pdev->dev, ": Could not register "
 					"Video for Linux device\n");
 			vfd->minor = -1;