dt-bindings: leds: Add 'cpuX' to 'linux,default-trigger'

Add 'cpu' and 'cpuN' to possible values for 'linux,default-trigger'.
There's 45 cases of them in upstream dts files.
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

Documentation/devicetree/bindings/leds/common.yaml

@@ -100,6 +100,7 @@ properties:
           - pattern
         # LED is triggered by SD/MMC activity
       - pattern: "^mmc[0-9]+$"
+      - pattern: "^cpu[0-9]*$"
 
   led-pattern:
     description: |