ARM: dts: kirkwood: Fix "debounce-interval" property misspelling

"debounce_interval" was never supported.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Cc: Jason Cooper <[e-mail]>
Cc: Andrew Lunn <[e-mail]>
Cc: Gregory Clement <[e-mail]>
Cc: Sebastian Hesselbarth <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Gregory CLEMENT <[e-mail]>

arch/arm/boot/dts/kirkwood-pogoplug-series-4.dts

···
 		pinctrl-names = "default";
 
 		eject {
-			debounce_interval = <50>;
+			debounce-interval = <50>;
 			wakeup-source;
 			linux,code = <KEY_EJECTCD>;
 			label = "Eject Button";