sound: Remove unnecessary casts of private_data

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/drivers/virmidi.c b/sound/drivers/virmidi.c
index 0e631c3..f4cd493 100644
--- a/sound/drivers/virmidi.c
+++ b/sound/drivers/virmidi.c
@@ -94,7 +94,7 @@
 			      sizeof(struct snd_card_virmidi), &card);
 	if (err < 0)
 		return err;
-	vmidi = (struct snd_card_virmidi *)card->private_data;
+	vmidi = card->private_data;
 	vmidi->card = card;
 
 	if (midi_devs[dev] > MAX_MIDI_DEVICES) {