ALSA: intel8x0: Mute External Amplifier by default for Gateway 4525GZ

BugLink: https://bugs.launchpad.net/bugs/487884

This Gateway model needs External Amplifier muted for audible playback,
so set the inv_eapd quirk for it.
Signed-off-by: Daniel T Chen <crimsun@ubuntu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/intel8x0.c

@@ -2062,6 +2062,12 @@ static struct ac97_quirk ac97_quirks[] __devinitdata = {
 		.name = "MSI P4 ATX 645 Ultra",
 		.type = AC97_TUNE_HP_ONLY
 	},
+	{
+		.subvendor = 0x161f,
+		.subdevice = 0x203a,
+		.name = "Gateway 4525GZ",		/* AD1981B */
+		.type = AC97_TUNE_INV_EAPD
+	},
 	{
 		.subvendor = 0x1734,
 		.subdevice = 0x0088,