dt-bindings: regulator: update fixed-regulator example

Fixed regulators do not have associated bus addresses and are typically
placed directly under the root node where their names must still be
unique despite not having a unit address.

Fix the malformed example node which had a unit address but no "reg"
property by dropping the unit address.

Also, try to make the example more useful by using the recommended
generic node name "regulator", but with a suffix reflecting the
regulator name in order to make it unique.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/fixed-regulator.yaml

@@ -52,9 +52,9 @@ required:
 
 examples:
   - |
-    abc: fixedregulator@0 {
+    reg_1v8: regulator-1v8 {
       compatible = "regulator-fixed";
-      regulator-name = "fixed-supply";
+      regulator-name = "1v8";
       regulator-min-microvolt = <1800000>;
       regulator-max-microvolt = <1800000>;
       gpio = <&gpio1 16 0>;