ALSA: hda - Fix parsing pin node 0x21 on ALC259

ALC259 has a widget NID 0x21 for the output pin, but it wasn't handled
properly in alc268_new_analog_output().

Signed-off-by: Takashi Iwai <tiwai@suse.de>

+1
+1
sound/pci/hda/patch_realtek.c
··· 12541 dac = 0x02; 12542 break; 12543 case 0x15: 12544 dac = 0x03; 12545 break; 12546 default:
··· 12541 dac = 0x02; 12542 break; 12543 case 0x15: 12544 + case 0x21: 12545 dac = 0x03; 12546 break; 12547 default: