ARM: dts: bcm2837-rpi-3-b-plus: Clarify label for STATUS_LED

The RPI 3 B+ provides control to both LEDs (PWR and ACT). So append
the first letter of the LED color (like in the schematics) in order
to clarify this.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

arch/arm/boot/dts/bcm2837-rpi-3-b-plus.dts

@@ -42,7 +42,7 @@ expgpio: gpio {
 		#gpio-cells = <2>;
 		gpio-line-names = "BT_ON",
 				  "WL_ON",
-				  "STATUS_LED",
+				  "STATUS_LED_R",
 				  "LAN_RUN",
 				  "",
 				  "CAM_GPIO0",