ARM: dts: am335x/am437x: remove unneeded unit name for gpio-keys nodes

This patch fixes the following DTC warnings for many boards:

"Node /gpio_keys/button0@10 has a unit name, but no reg property"

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
index 63124f8..944914e 100644
--- a/arch/arm/boot/dts/am335x-evm.dts
+++ b/arch/arm/boot/dts/am335x-evm.dts
@@ -73,20 +73,20 @@
 				0x0201006c>;	/* DOWN */
 	};
 
-	gpio_keys: volume_keys@0 {
+	gpio_keys: volume_keys0 {
 		compatible = "gpio-keys";
 		#address-cells = <1>;
 		#size-cells = <0>;
 		autorepeat;
 
-		switch@9 {
+		switch9 {
 			label = "volume-up";
 			linux,code = <115>;
 			gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;
 			wakeup-source;
 		};
 
-		switch@10 {
+		switch10 {
 			label = "volume-down";
 			linux,code = <114>;
 			gpios = <&gpio0 3 GPIO_ACTIVE_LOW>;