ALSA: sound/core: use memdup_user()

Remove open-coded memdup_user().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 3f0050d..8f8b17a 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -1395,13 +1395,10 @@
 	struct list_head *p;
 	int err = 0;
 
-	ginfo = kmalloc(sizeof(*ginfo), GFP_KERNEL);
-	if (! ginfo)
-		return -ENOMEM;
-	if (copy_from_user(ginfo, _ginfo, sizeof(*ginfo))) {
-		kfree(ginfo);
-		return -EFAULT;
-	}
+	ginfo = memdup_user(_ginfo, sizeof(*ginfo));
+	if (IS_ERR(ginfo))
+		return PTR_ERR(ginfo);
+
 	tid = ginfo->tid;
 	memset(ginfo, 0, sizeof(*ginfo));
 	ginfo->tid = tid;