pinctrl: mediatek: Bind gpio while binding pinctrl

Mediatek pinctrl drivers call mtk_gpiochip_register() to bind the child
gpio controller as part of mtk_pinctrl_common_probe(). This breaks
gpiohog support because the gpio controller is bound too late for
DM_FLAG_PROBE_AFTER_BIND (set while binding hogs) to work.

Move the mtk_gpiochip_register() to mtk_pinctrl_common_bind() and call
this as the .bind method of each of the mediatek pinctrl drivers.

Signed-off-by: Chris Webb <chris@arachsys.com>
diff --git a/drivers/pinctrl/mediatek/pinctrl-mt8516.c b/drivers/pinctrl/mediatek/pinctrl-mt8516.c
index 7487d6f..9c25066 100644
--- a/drivers/pinctrl/mediatek/pinctrl-mt8516.c
+++ b/drivers/pinctrl/mediatek/pinctrl-mt8516.c
@@ -388,6 +388,7 @@
 	.id = UCLASS_PINCTRL,
 	.of_match = mt8516_pctrl_match,
 	.ops = &mtk_pinctrl_ops,
+	.bind = mtk_pinctrl_common_bind,
 	.probe = mtk_pinctrl_mt8516_probe,
 	.priv_auto	= sizeof(struct mtk_pinctrl_priv),
 };