ALSA: hda - Fix silent output on MacBook Air 1,1

Similarly to other Apple products, MBA 1,1 needs a specific quirk.
Pin 0x18 must be set to VREF_50 to have sound output. This was no
longer done since commit 1a97b7f, resulting in a mute built-in speaker.

This patch corrects the regression by creating a fixup for the MBA 1,1.

Fixes: 1a97b7f22774 ("ALSA: hda/realtek - Remove the last static quirks for ALC882")
Cc: <[e-mail]> [v3.4+]
Tested-by: Adrien Vergé <[e-mail]>
Signed-off-by: Adrien Vergé <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/pci/hda/patch_realtek.c

···
 	ALC889_FIXUP_DAC_ROUTE,
 	ALC889_FIXUP_MBP_VREF,
 	ALC889_FIXUP_IMAC91_VREF,
+	ALC889_FIXUP_MBA11_VREF,
 	ALC889_FIXUP_MBA21_VREF,
 	ALC882_FIXUP_INV_DMIC,
 	ALC882_FIXUP_NO_PRIMARY_HP,
···
 				     const struct hda_fixup *fix, int action)
 {
 	static hda_nid_t nids[2] = { 0x18, 0x1a };
+
+	if (action == HDA_FIXUP_ACT_INIT)
+		alc889_fixup_mac_pins(codec, nids, ARRAY_SIZE(nids));
+}
+
+/* Set VREF on speaker pins on mba11 */
+static void alc889_fixup_mba11_vref(struct hda_codec *codec,
+				    const struct hda_fixup *fix, int action)
+{
+	static hda_nid_t nids[1] = { 0x18 };
 
 	if (action == HDA_FIXUP_ACT_INIT)
 		alc889_fixup_mac_pins(codec, nids, ARRAY_SIZE(nids));
···
 		.chained = true,
 		.chain_id = ALC882_FIXUP_GPIO1,
 	},
+	[ALC889_FIXUP_MBA11_VREF] = {
+		.type = HDA_FIXUP_FUNC,
+		.v.func = alc889_fixup_mba11_vref,
+		.chained = true,
+		.chain_id = ALC889_FIXUP_MBP_VREF,
+	},
 	[ALC889_FIXUP_MBA21_VREF] = {
 		.type = HDA_FIXUP_FUNC,
 		.v.func = alc889_fixup_mba21_vref,
···
 	SND_PCI_QUIRK(0x106b, 0x2c00, "MacbookPro rev3", ALC889_FIXUP_MBP_VREF),
 	SND_PCI_QUIRK(0x106b, 0x3000, "iMac", ALC889_FIXUP_MBP_VREF),
 	SND_PCI_QUIRK(0x106b, 0x3200, "iMac 7,1 Aluminum", ALC882_FIXUP_EAPD),
-	SND_PCI_QUIRK(0x106b, 0x3400, "MacBookAir 1,1", ALC889_FIXUP_MBP_VREF),
+	SND_PCI_QUIRK(0x106b, 0x3400, "MacBookAir 1,1", ALC889_FIXUP_MBA11_VREF),
 	SND_PCI_QUIRK(0x106b, 0x3500, "MacBookAir 2,1", ALC889_FIXUP_MBA21_VREF),
 	SND_PCI_QUIRK(0x106b, 0x3600, "Macbook 3,1", ALC889_FIXUP_MBP_VREF),
 	SND_PCI_QUIRK(0x106b, 0x3800, "MacbookPro 4,1", ALC889_FIXUP_MBP_VREF),