Documentation: Move common leds properties description to separate file.

There are several drivers that use LEDs and depend on exactly the same
device tree binding. However, the binding documentation has simply been
cut-and-paste into each of the binding documents. Rather than continue
to duplicate it, this patch adds a common led binding document that all
can reference.
Signed-off-by: Marek Belisko <marek.belisko@open-nandra.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/gpio/led.txt

@@ -10,16 +10,10 @@ LED sub-node properties:
 - gpios :  Should specify the LED's GPIO, see "gpios property" in
   Documentation/devicetree/bindings/gpio/gpio.txt.  Active low LEDs should be
   indicated using flags in the GPIO specifier.
-- label :  (optional) The label for this LED.  If omitted, the label is
-  taken from the node name (excluding the unit address).
-- linux,default-trigger :  (optional) This parameter, if present, is a
-  string defining the trigger assigned to the LED.  Current triggers are:
-    "backlight" - LED will act as a back-light, controlled by the framebuffer
-		  system
-    "default-on" - LED will turn on, but see "default-state" below
-    "heartbeat" - LED "double" flashes at a load average based rate
-    "ide-disk" - LED indicates disk activity
-    "timer" - LED flashes at a fixed, configurable rate
+- label :  (optional)
+  see Documentation/devicetree/bindings/leds/common.txt
+- linux,default-trigger :  (optional)
+  see Documentation/devicetree/bindings/leds/common.txt
 - default-state:  (optional) The initial state of the LED.  Valid
   values are "on", "off", and "keep".  If the LED is already on or off
   and the default-state property is set the to same value, then no

Documentation/devicetree/bindings/leds/common.txt

+Common leds properties.
+
+Optional properties for child nodes:
+- label : The label for this LED.  If omitted, the label is
+  taken from the node name (excluding the unit address).
+
+- linux,default-trigger :  This parameter, if present, is a
+    string defining the trigger assigned to the LED.  Current triggers are:
+     "backlight" - LED will act as a back-light, controlled by the framebuffer
+		   system
+     "default-on" - LED will turn on (but for leds-gpio see "default-state"
+		    property in Documentation/devicetree/bindings/gpio/led.txt)
+     "heartbeat" - LED "double" flashes at a load average based rate
+     "ide-disk" - LED indicates disk activity
+     "timer" - LED flashes at a fixed, configurable rate
+
+Examples:
+
+system-status {
+	label = "Status";
+	linux,default-trigger = "heartbeat";
+	...
+};