dt-bindings: pinctrl: renesas,rza2-pinctrl: Fix pin controller node name

According to Devicetree Specification v0.2 and later, Section "Generic
Names Recommendation", the node name for a pin controller device node
should be "pinctrl".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200821111127.3771-1-geert+renesas@glider.be

Documentation/devicetree/bindings/pinctrl/renesas,rza2-pinctrl.yaml

@@ -84,7 +84,7 @@ additionalProperties: false
 examples:
   - |
     #include <dt-bindings/pinctrl/r7s9210-pinctrl.h>
-    pinctrl: pin-controller@fcffe000 {
+    pinctrl: pinctrl@fcffe000 {
             compatible = "renesas,r7s9210-pinctrl";
             reg = <0xfcffe000 0x1000>;