ASoC: simple-card: is GPL v2

It is indicating that this driver is GPL v2 on top of C code.
Let's fixup it on MODULE_LICENSE()

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/generic/simple-card.c

@@ -498,6 +498,6 @@ static struct platform_driver asoc_simple_card = {
 module_platform_driver(asoc_simple_card);
 
 MODULE_ALIAS("platform:asoc-simple-card");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("ASoC Simple Sound Card");
 MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");