dt-bindings: Use lower case hex in unit-addresses

DT unit addresses should be lower case hex. Fix all the
binding examples.

Converted with the following command from Krzysztof Kozlowski:

sed -e 's/@\([a-fA-F0-9_-]*\) {/@\L\1 {/' -i $(find Documentation/devicetree/bindings -name '*.txt')

Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/devfreq/event/exynos-nocp.txt

@@ -20,7 +20,7 @@ Optional properties:
 
 Example : NoC Probe nodes in Device Tree are listed below.
 
-	nocp_mem0_0: nocp@10CA1000 {
+	nocp_mem0_0: nocp@10ca1000 {
 		compatible = "samsung,exynos5420-nocp";
 		reg = <0x10CA1000 0x200>;
 	};