ALSA: intel8x0: Fix default inaudible sound on Gateway M520

BugLink: https://bugs.launchpad.net/bugs/930842

The reporter states that audio is inaudible by default without muting
'External Amplifier'. Add a quirk to handle his SSID so that changing
the control is not necessary.
Reported-and-tested-by: Benjamin Carlson <elderbubba0810@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Daniel T Chen <crimsun@ubuntu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/intel8x0.c

@@ -2100,6 +2100,12 @@ static struct ac97_quirk ac97_quirks[] __devinitdata = {
 		.name = "MSI P4 ATX 645 Ultra",
 		.type = AC97_TUNE_HP_ONLY
 	},
+	{
+		.subvendor = 0x161f,
+		.subdevice = 0x202f,
+		.name = "Gateway M520",
+		.type = AC97_TUNE_INV_EAPD
+	},
 	{
 		.subvendor = 0x161f,
 		.subdevice = 0x203a,