fixed example devicetree basics

Author: m0veax

source/chapter2-devicetree-basics.rst

@@ -1251,11 +1251,11 @@ interrupt controller.
       #address-cells = <1>;
       #size-cells = <1>;
 
-      open-pic {
+      open_pic: pic@13370000 {
          clock-frequency = <0>;
          interrupt-controller;
          #address-cells = <0>;
-         #interrupt-cells = <2>;
+         #interrupt-cells = <2>
       };
 
       pci {