ALSA: hda - Fix mono speakers and headset mic on Dell Vostro 5470

ALSA: hda - Fix mono speakers and headset mic on Dell Vostro 5470

This is a backport for stable. The original commit SHA is
338cae565c53755de9f87d6a801517940d2d56f7.

On this machine, DAC on node 0x03 seems to give mono output.

Also, it needs additional patches for headset mic support.
It supports CTIA style headsets only.

Alsa-info available at the bug link below.

BugLink: https://bugs.launchpad.net/bugs/1236228
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>