ALSA: hda: prevent undefined shift in snd_hdac_ext_bus_get_link()

This is harmless, but the "addr" comes from the user and it could lead
to a negative shift or to shift wrapping if it's too high.

Fixes: 0b00a561 ("ALSA: hdac_ext: add hdac extended controller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20201103101807.GC1127762@mwandaSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/hda/ext/hdac_ext_controller.c

@@ -148,6 +148,8 @@ struct hdac_ext_link *snd_hdac_ext_bus_get_link(struct hdac_bus *bus,
 		return NULL;
 	if (bus->idx != bus_idx)
 		return NULL;
+	if (addr < 0 || addr > 31)
+		return NULL;
 
 	list_for_each_entry(hlink, &bus->hlink_list, list) {
 		for (i = 0; i < HDA_MAX_CODECS; i++) {