ASoC: tpa6130a2: Support for limiting gain

Add support for platform dependent gain limiting on the
tpa6130a2 (and tpa6140a2) Headset amplifier.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

include/sound/tpa6130a2-plat.h

@@ -31,6 +31,7 @@ enum tpa_model {
 struct tpa6130a2_platform_data {
 	enum tpa_model id;
 	int power_gpio;
+	int limit_gain;
 };
 
 #endif