dt-bindings: auxdisplay: adjust example indentation and use generic node names

The example DTS should be indented with two or four (preferred) spaces,
as mentioned in Writing Schema document.  While re-indenting, change the
node names to somehow generic names, as expected by Devicetree
specification.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Schlatterbeck <rsc@runtux.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml

@@ -84,7 +84,7 @@ additionalProperties: false
 examples:
   - |
     #include <dt-bindings/gpio/gpio.h>
-    auxdisplay {
+    display-controller {
         compatible = "hit,hd44780";
 
         data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>,
@@ -97,20 +97,22 @@ examples:
         display-height-chars = <2>;
         display-width-chars = <16>;
     };
+
   - |
     #include <dt-bindings/gpio/gpio.h>
     i2c {
         #address-cells = <1>;
         #size-cells = <0>;
 
-            pcf8574: pcf8574@27 {
+        pcf8574: gpio-expander@27 {
             compatible = "nxp,pcf8574";
             reg = <0x27>;
             gpio-controller;
             #gpio-cells = <2>;
         };
     };
-    hd44780 {
+
+    display-controller {
         compatible = "hit,hd44780";
         display-height-chars = <2>;
         display-width-chars = <16>;

Documentation/devicetree/bindings/auxdisplay/holtek,ht16k33.yaml

@@ -77,7 +77,7 @@ examples:
         #address-cells = <1>;
         #size-cells = <0>;
 
-            ht16k33: ht16k33@70 {
+        display-controller@70 {
             compatible = "holtek,ht16k33";
             reg = <0x70>;
             refresh-rate-hz = <20>;