dt-bindings: i2c: aspeed: drop redundant multi-master

'multi-master' property is defined by core i2c-controller schema in
dtschema package, so binding which references it and has
unevaluatedProperties:false, does not need to mention it. It is
completely redundant here.

Suggested-by: Andi Shyti <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Signed-off-by: Andi Shyti <[e-mail]>

Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml

···
     description: frequency of the bus clock in Hz defaults to 100 kHz when not
       specified
 
-  multi-master:
-    type: boolean
-    description:
-      states that there is another master active on this bus
-
 required:
   - reg
   - compatible