dt-bindings: ipmi: aspeed,ast2400-kcs-bmc: Add missing "clocks" property

The ASpeed kcs-bmc nodes have a "clocks" property which isn't
documented. It looks like all the LPC child devices have the same clock
source and some of the drivers manage their clock. Perhaps it is the
parent device that should have the clock, but it's too late for that.

Signed-off-by: Rob Herring (Arm) <[e-mail]>
Message-ID: <[e-mail]>
Signed-off-by: Corey Minyard <[e-mail]>

Documentation/devicetree/bindings/ipmi/aspeed,ast2400-kcs-bmc.yaml

···
       - description: ODR register
       - description: STR register
 
+  clocks:
+    maxItems: 1
+
   aspeed,lpc-io-reg:
     $ref: /schemas/types.yaml#/definitions/uint32-array
     minItems: 1