ALSA: hda - Add a quirk for Dell Studio 15

Added the matching model=dell-m6 for Dell Studio 15 laptop.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/patch_sigmatel.c b/sound/pci/hda/patch_sigmatel.c
index 9047dc7..2b52a40 100644
--- a/sound/pci/hda/patch_sigmatel.c
+++ b/sound/pci/hda/patch_sigmatel.c
@@ -1630,6 +1630,8 @@
 				"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 */
 };