ALSA: hda - Set codec->single_adc_amp flag for Realtek codecs

It turned out that Realtek codecs (ALC260, etc) with input amps in
audio-input widgets don't handle the multiple individual input amps.
Thus we need to set codec->single_adc_amp flag for them in general.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_realtek.c

@@ -4373,6 +4373,7 @@ static int alc_alloc_spec(struct hda_codec *codec, hda_nid_t mixer_nid)
 	if (!spec)
 		return -ENOMEM;
 	codec->spec = spec;
+	codec->single_adc_amp = 1;
 	spec->mixer_nid = mixer_nid;
 	snd_hda_gen_init(&spec->gen);
 	snd_array_init(&spec->kctls, sizeof(struct snd_kcontrol_new), 32);