ALSA: hda: Use struct_size()

For code simplification and safety, use struct_size() macro for
calculating the hda_conn_list object size with the variable array.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_codec.c

@@ -122,7 +122,7 @@ static int add_conn_list(struct hda_codec *codec, hda_nid_t nid, int len,
 {
 	struct hda_conn_list *p;
 
-	p = kmalloc(sizeof(*p) + len * sizeof(hda_nid_t), GFP_KERNEL);
+	p = kmalloc(struct_size(p, conns, len), GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
 	p->len = len;