dt-bindings: power: Fix "debounce-interval" property misspelling

"debounce_interval" was never supported.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/power/wakeup-source.txt

@@ -60,7 +60,7 @@ Examples
 		#size-cells = <0>;
 
 		button@1 {
-			debounce_interval = <50>;
+			debounce-interval = <50>;
 			wakeup-source;
 			linux,code = <116>;
 			label = "POWER";