em28xx-alsa: Fix error patch for init/fini

If something bad happens during init, we free the card data.
However, we still keep it initialized, causing some dependent
code to be called at .fini.

Fix it.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

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

@@ -948,6 +948,7 @@ static int em28xx_audio_init(struct em28xx *dev)
 
 card_free:
 	snd_card_free(card);
+	adev->sndcard = NULL;
 
 	return err;
 }
@@ -966,12 +967,12 @@ static int em28xx_audio_fini(struct em28xx *dev)
 
 	em28xx_info("Closing audio extension");
 
-	snd_card_disconnect(dev->adev.sndcard);
-	flush_work(&dev->wq_trigger);
+	if (dev->adev.sndcard) {
+		snd_card_disconnect(dev->adev.sndcard);
+		flush_work(&dev->wq_trigger);
 
-	em28xx_audio_free_urb(dev);
+		em28xx_audio_free_urb(dev);
 
-	if (dev->adev.sndcard) {
 		snd_card_free(dev->adev.sndcard);
 		dev->adev.sndcard = NULL;
 	}