ASoC: mediatek: mt8183: remove forward declaration of headset_init

The forward declaration of mt8183_mt6358_ts3a227_max98357_headset_init
is for cyclic dependency between card, headset_dev, and headset_init.

It used to be:
- card depends on headset_dev
- headset_dev depends on headset_init
- headset_init depends on card

Commit a962a809 ("ASoC: mediatek: mt8183: make headset codec
optional") removed the cyclic dependency.

Thus, it is safe to remove the forward declaration.
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20190830074240.195166-4-tzungbi@google.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/mediatek/mt8183/mt8183-mt6358-ts3a227-max98357.c

@@ -390,14 +390,6 @@ mt8183_mt6358_ts3a227_max98357_dai_links[] = {
 	},
 };
 
-static int
-mt8183_mt6358_ts3a227_max98357_headset_init(struct snd_soc_component *cpnt);
-
-static struct snd_soc_aux_dev mt8183_mt6358_ts3a227_max98357_headset_dev = {
-	.dlc = COMP_EMPTY(),
-	.init = mt8183_mt6358_ts3a227_max98357_headset_init,
-};
-
 static struct snd_soc_card mt8183_mt6358_ts3a227_max98357_card = {
 	.name = "mt8183_mt6358_ts3a227_max98357",
 	.owner = THIS_MODULE,
@@ -428,6 +420,11 @@ mt8183_mt6358_ts3a227_max98357_headset_init(struct snd_soc_component *component)
 	return ret;
 }
 
+static struct snd_soc_aux_dev mt8183_mt6358_ts3a227_max98357_headset_dev = {
+	.dlc = COMP_EMPTY(),
+	.init = mt8183_mt6358_ts3a227_max98357_headset_init,
+};
+
 static int
 mt8183_mt6358_ts3a227_max98357_dev_probe(struct platform_device *pdev)
 {