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

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.

Cc: stable@kernel.org (v3.10+)
BugLink: https://bugs.launchpad.net/bugs/1236228
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>