powerpc/83xx: Add MCU LEDs support for MPC837xRDB and MPC8315RDB boards

There are two front-panel LEDs on MPC837xRDB and MPC8315RDB boards: PWR
and HDD. After adding appropriate nodes we can program these LEDs from
kernel and user space.

Signed-off-by: Anton Vorontsov <avorontsov@mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/dts/mpc8377_rdb.dts

@@ -486,4 +486,18 @@
 				  0 0x00800000>;
 		};
 	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		pwr {
+			gpios = <&mcu_pio 0 0>;
+			default-state = "on";
+		};
+
+		hdd {
+			gpios = <&mcu_pio 1 0>;
+			linux,default-trigger = "ide-disk";
+		};
+	};
 };