ALSA: atmel/ac97c: correct the unexpected behavior when using uninitial value for reset pin

When pdata->reset_pin is passed with a negative value (means gpio
is invalid), then chip->reset_pin will not be assigned to a vaule,
it will use default value 0. This will cause unexpected behavior.

So, add this patch to correct.
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/atmel/ac97c.c

@@ -991,6 +991,8 @@ static int __devinit atmel_ac97c_probe(struct platform_device *pdev)
 			gpio_direction_output(pdata->reset_pin, 1);
 			chip->reset_pin = pdata->reset_pin;
 		}
+	} else {
+		chip->reset_pin = -EINVAL;
 	}
 
 	snd_card_set_dev(card, &pdev->dev);