dt-bindings: opp: Support multiple opp-suspend properties

Update opp-suspend property's description to support multiple
opp-suspend properties defined in DT, the OPP with highest opp-hz
and with opp-suspend property present will be used as suspend opp.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Documentation/devicetree/bindings/opp/opp.txt

@@ -140,8 +140,8 @@ Optional properties:
   frequency for a short duration of time limited by the device's power, current
   and thermal limits.
 
-- opp-suspend: Marks the OPP to be used during device suspend. Only one OPP in
-  the table should have this.
+- opp-suspend: Marks the OPP to be used during device suspend. If multiple OPPs
+  in the table have this, the OPP with highest opp-hz will be used.
 
 - opp-supported-hw: This enables us to select only a subset of OPPs from the
   larger OPP table, based on what version of the hardware we are running on. We