dt-bindings: thermal: Fix definition of cooling-maps contribution property

When converting the thermal-zones bindings to yaml the definition of the
contribution property changed. The intention is the same, an integer
value expressing a ratio of a sum on how much cooling is provided by the
device to the zone. But after the conversion the integer value is
limited to the range 0 to 100 and expressed as a percentage.

This is problematic for two reasons.

- This do not match how the binding is used. Out of the 18 files that
  make use of the property only two (ste-dbx5x0.dtsi and
  ste-hrefv60plus.dtsi) sets it at a value that satisfy the binding,
  100. The remaining 16 files set the value higher and fail to validate.

- Expressing the value as a percentage instead of a ratio of the sum is
  confusing as there is nothing to enforce the sum in the zone is not
  greater then 100.

This patch restore the pre yaml conversion description and removes the
value limitation allowing the usage of the bindings to validate.

Fixes: 1202a442a3 ("dt-bindings: thermal: Add yaml bindings for thermal zones")
Reported-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20211109103045.1403686-1-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/thermal/thermal-zones.yaml

@@ -199,12 +199,11 @@ patternProperties:
 
               contribution:
                 $ref: /schemas/types.yaml#/definitions/uint32
-                minimum: 0
-                maximum: 100
                 description:
-                  The percentage contribution of the cooling devices at the
-                  specific trip temperature referenced in this map
-                  to this thermal zone
+                  The cooling contribution to the thermal zone of the referred
+                  cooling device at the referred trip point. The contribution is
+                  a ratio of the sum of all cooling contributions within a
+                  thermal zone.
 
             required:
               - trip