ALSA: hda/realtek - Fix silent headphone output on MacPro 4,1 (v2)

commit 9f660a1c43890c2cdd1f423fd73654e7ca08fe56 upstream.

Without this patch, internal speaker and line-out work,
but front headphone output jack stays silent on the
Mac Pro 4,1.

This code path also gets executed on the MacPro 5,1 due
to identical codec SSID, but i don't know if it has any
positive or adverse effects there or not.

(v2) Implement feedback from Takashi Iwai: Reuse
     alc889_fixup_mbp_vref and just add a new nid
     0x19 for the MacPro 4,1.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>