SF: Move desired active mode management to DisplayDevice

SF would set the desired active mode on the specific DisplayDevice the
mode was requested and use it to swicth the active display mode.

Change-Id: Ib4f01ec63b2087ab2a81490051d1e029afc71854
Test: SF unit tests
Test: refresh rate switching is working on device with
more than one display
Bug: 187539899

Change-Id: Ie0e5ffe364f81775c2101ffd0cf2c596051947fa
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 5fc19da..4a9a1fd 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -71,6 +71,7 @@
         int32_t getModeGroup() const { return mode->getGroup(); }
         std::string getName() const { return to_string(getFps()); }
         Fps getFps() const { return mode->getFps(); }
+        DisplayModePtr getMode() const { return mode; }
 
         // Checks whether the fps of this RefreshRate struct is within a given min and max refresh
         // rate passed in. Margin of error is applied to the boundaries for approximation.