ALSA: hda - Enable subwoofer on Dell Vostro 5460/5470

In this case, there are two DACs, and DAC 0x03 is mono. In order
to make headphones and front speaker use DAC 0x02, and subwoofer use
DAC 0x03, we artificially cut the connection from nodes 0x14 and 0x15
to node 0x03, so they can only use DAC 0x02.

In addition, the 5460 and 5470 differs in the sense that 5470 also
needs a headset mic patch, whereas 5460 has individual detection for
headphone and headset mic.

BugLink: https://bugs.launchpad.net/bugs/1211920


Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>