dm: pinctrl: Skip gpio-controller node in pinconfig_post_bind()

Some binding define child node gpio-controller without compatible property.
This patch avoid to bind the pinconfig uclass to these node.

For example, the binding for st,stm32-pinctrl
(./device-tree-bindings/pinctrl/st,stm32-pinctrl.txt) defines the GPIO
controller/bank node as sub-node of pincontrol (st,stm32f429-pinctrl)
but without compatible (as it is not mandatory).

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pinctrl/pinctrl-uclass.c b/drivers/pinctrl/pinctrl-uclass.c
index 4e6cef8..0e6c559 100644
--- a/drivers/pinctrl/pinctrl-uclass.c
+++ b/drivers/pinctrl/pinctrl-uclass.c
@@ -127,6 +127,9 @@
 		ofnode_get_property(node, "compatible", &ret);
 		if (ret >= 0)
 			continue;
+		/* If this node has "gpio-controller" property, skip */
+		if (ofnode_read_bool(node, "gpio-controller"))
+			continue;
 
 		if (ret != -FDT_ERR_NOTFOUND)
 			return ret;