ALSA: mtpav: Remove redundant platform_set_drvdata()

Commit 0998d06310 (device-core: Ensure drvdata = NULL when no
driver is bound) removes the need to set driver data field to
NULL.

Signed-off-by: Sachin Kamat <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/drivers/mtpav.c

···
 static int snd_mtpav_remove(struct platform_device *devptr)
 {
 	snd_card_free(platform_get_drvdata(devptr));
-	platform_set_drvdata(devptr, NULL);
 	return 0;
 }