ALSA: hda - fix the mic mute led problem for Latitude E5550

The microphone mute led on the Latitude E5550 can't work. We need to
apply DELL_WMI_MIC_MUTE_LED quirk to this machine.

The machine uses alc293 codec and already applied the quirk
ALC293_FIXUP_DELL1_MIC_NO_PRESENCE through pin_fixup_tbl[].

Here we just let DELL_WMI_MIC_MUTE_LED be chained to
ALC269_FIXUP_HEADSET_MODE, then the machine will have these
quirks ALC293_FIXUP_DELL1_MIC_NO_PRESENCE-->
ALC269_FIXUP_HEADSET_MODE-->ALC255_FIXUP_DELL_WMI_MIC_MUTE_LED.

BugLink: https://bugs.launchpad.net/bugs/1381856
Reported-and-tested-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
index 9da5798..8fea1b8 100644
--- a/sound/pci/hda/patch_realtek.c
+++ b/sound/pci/hda/patch_realtek.c
@@ -4520,6 +4520,8 @@
 	[ALC269_FIXUP_HEADSET_MODE] = {
 		.type = HDA_FIXUP_FUNC,
 		.v.func = alc_fixup_headset_mode,
+		.chained = true,
+		.chain_id = ALC255_FIXUP_DELL_WMI_MIC_MUTE_LED
 	},
 	[ALC269_FIXUP_HEADSET_MODE_NO_HP_MIC] = {
 		.type = HDA_FIXUP_FUNC,