ALSA: hda - Add Conexant codecs CX20721, CX20722, CX20723 and CX20724

commit 6ffc0898b29a2811a6c0569c5dd9b581980110df upstream.

This patch adds support for Conexant HD Audio codecs
CX20721, CX20722, CX20723 and CX20724.

BugLink: https://bugs.launchpad.net/bugs/1454656


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>