ALSA: HDA: Use one dmic only for Dell Studio 1558

There are no signs of a dmic at node 0x0b, so the user is left with
an additional internal mic which does not exist. This commit removes
that non-existing mic.

Cc: stable@kernel.org (2.6.32+)
BugLink: http://bugs.launchpad.net/bugs/731706Reported-by: James Page <james.page@canonical.com>
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_sigmatel.c

@@ -1604,7 +1604,7 @@ static const struct snd_pci_quirk stac92hd73xx_cfg_tbl[] = {
 	SND_PCI_QUIRK(PCI_VENDOR_ID_DELL, 0x02fe,
 				"Dell Studio XPS 1645", STAC_DELL_M6_BOTH),
 	SND_PCI_QUIRK(PCI_VENDOR_ID_DELL, 0x0413,
-				"Dell Studio 1558", STAC_DELL_M6_BOTH),
+				"Dell Studio 1558", STAC_DELL_M6_DMIC),
 	{} /* terminator */
 };