[media] em28xx-v4l: do not call em28xx_init_camera() if the device has no sensor

This avoids the unnecessary temporary registration of a dummy V4L2 clock.
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/usb/em28xx/em28xx-video.c

@@ -2273,7 +2273,8 @@ static int em28xx_v4l2_init(struct em28xx *dev)
 	}
 
 	em28xx_tuner_setup(dev);
-	em28xx_init_camera(dev);
+	if (dev->em28xx_sensor != EM28XX_NOSENSOR)
+		em28xx_init_camera(dev);
 
 	/* Configure audio */
 	ret = em28xx_audio_setup(dev);