dt-bindings: net: sff,sfp: update binding

Add a minimum and default for the maximum-power-milliwatt option;
module power levels were originally up to 1W, so this is the default
and the minimum power level we can have for a functional SFP cage.

Signed-off-by: Russell King (Oracle) <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/devicetree/bindings/net/sff,sfp.yaml

···
       phandle of an I2C bus controller for the SFP two wire serial
 
   maximum-power-milliwatt:
-    maxItems: 1
+    minimum: 1000
+    default: 1000
     description:
       Maximum module power consumption Specifies the maximum power consumption
       allowable by a module in the slot, in milli-Watts. Presently, modules can