dts: add missing linux,code in gpio-keys

gpio-keys linux driver enforces user to specify linux,code.
Add missing linux,code before implementing button input support.

- arch/arm/dts/rk3288-popmetal.dtsi -> KEY_POWER
- arch/arm/dts/rk3288-tinker.dtsi -> KEY_POWER
- arch/arm/dts/am3517-evm-ui.dtsi -> KEY_RECORD
- sandbox/dts/sandbox.dtsi -> BTN_1
- sandbox/dts/sandbox.dts -> BTN_1

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/am3517-evm-ui.dtsi b/arch/arm/dts/am3517-evm-ui.dtsi
index 7d8f32b..340e681 100644
--- a/arch/arm/dts/am3517-evm-ui.dtsi
+++ b/arch/arm/dts/am3517-evm-ui.dtsi
@@ -72,7 +72,7 @@
 
 		record {
 			label = "Record";
-			/* linux,code = <BTN_0>; */
+			linux,code = <KEY_RECORD>;
 			gpios = <&tca6416_2 15 GPIO_ACTIVE_LOW>;
 		};
 
diff --git a/arch/arm/dts/imx6ul-phytec-segin-peb-eval-01.dtsi b/arch/arm/dts/imx6ul-phytec-segin-peb-eval-01.dtsi
index 2f3fd32..5f760ed 100644
--- a/arch/arm/dts/imx6ul-phytec-segin-peb-eval-01.dtsi
+++ b/arch/arm/dts/imx6ul-phytec-segin-peb-eval-01.dtsi
@@ -8,7 +8,7 @@
 
 / {
 	gpio_keys: gpio-keys {
-		compatible = "gpio-key";
+		compatible = "gpio-keys";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_gpio_keys>;
 		status = "disabled";
diff --git a/arch/arm/dts/rk3288-popmetal.dtsi b/arch/arm/dts/rk3288-popmetal.dtsi
index 63785eb..0253933 100644
--- a/arch/arm/dts/rk3288-popmetal.dtsi
+++ b/arch/arm/dts/rk3288-popmetal.dtsi
@@ -38,6 +38,7 @@
  *     OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <dt-bindings/input/input.h>
 #include "rk3288.dtsi"
 
 / {
@@ -63,6 +64,7 @@
 		power {
 			gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
 			label = "GPIO Key Power";
+			linux,code = <KEY_POWER>;
 			linux,input-type = <1>;
 			wakeup-source;
 			debounce-interval = <100>;
diff --git a/arch/arm/dts/rk3288-tinker.dtsi b/arch/arm/dts/rk3288-tinker.dtsi
index 2f816af..46460ae 100644
--- a/arch/arm/dts/rk3288-tinker.dtsi
+++ b/arch/arm/dts/rk3288-tinker.dtsi
@@ -38,6 +38,7 @@
  *     OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <dt-bindings/input/input.h>
 #include "rk3288.dtsi"
 
 / {
@@ -63,6 +64,7 @@
 		button@0 {
 			gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
 			label = "GPIO Key Power";
+			linux,code = <KEY_POWER>;
 			linux,input-type = <1>;
 			gpio-key,wakeup = <1>;
 			debounce-interval = <100>;
diff --git a/arch/sandbox/dts/sandbox.dtsi b/arch/sandbox/dts/sandbox.dtsi
index 18bf1cb..7e7fcff 100644
--- a/arch/sandbox/dts/sandbox.dtsi
+++ b/arch/sandbox/dts/sandbox.dtsi
@@ -4,6 +4,8 @@
  * and sandbox64 builds.
  */
 
+#include <dt-bindings/input/input.h>
+
 #define USB_CLASS_HUB			9
 
 / {
@@ -36,11 +38,13 @@
 		btn1 {
 			gpios = <&gpio_a 3 0>;
 			label = "button1";
+		    linux,code = <BTN_1>;
 		};
 
 		btn2 {
 			gpios = <&gpio_a 4 0>;
 			label = "button2";
+		    linux,code = <BTN_2>;
 		};
 	};