ALSA: hda - Add a quirk for Dell Studio 15

Added the matching model=dell-m6 for Dell Studio 15 laptop.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_sigmatel.c

@@ -1630,6 +1630,8 @@ static struct snd_pci_quirk stac92hd73xx_cfg_tbl[] = {
 				"unknown Dell", STAC_DELL_M6),
 	SND_PCI_QUIRK(PCI_VENDOR_ID_DELL, 0x0271,
 				"unknown Dell", STAC_DELL_M6),
+	SND_PCI_QUIRK(PCI_VENDOR_ID_DELL, 0x029f,
+				"Dell Studio 15", STAC_DELL_M6),
 	{} /* terminator */
 };