ALSA: hda - simplify usage of HDA_SUBDEV_AMP_FLAG

The HDA_SUBDEV_NID_FLAG is duplicate for amplifier control elements. Move
get_amp_nid_() call to the snd_hda_ctl_add() function.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/pci/hda/patch_conexant.c b/sound/pci/hda/patch_conexant.c
index b68650a..1ab2958 100644
--- a/sound/pci/hda/patch_conexant.c
+++ b/sound/pci/hda/patch_conexant.c
@@ -2178,7 +2178,7 @@
 		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
 				  SNDRV_CTL_ELEM_ACCESS_TLV_READ |
 				  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK,
-		.subdevice = HDA_SUBDEV_NID_FLAG | HDA_SUBDEV_AMP_FLAG | 0x10,
+		.subdevice = HDA_SUBDEV_AMP_FLAG,
 		.info = snd_hda_mixer_amp_volume_info,
 		.get = snd_hda_mixer_amp_volume_get,
 		.put = snd_hda_mixer_amp_volume_put,