Rename RefreshRateOverlay vsyncRate to RefreshRate

With MRR devices, vsyncRate and refreshRate are the same thing, but
this is not true for dVRR devices.

Test: manually test refresh rate indicator
Change-Id: I0946ad4164257b1919035a0db1080ec06ba1ed53
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index fc5089b..db1b23d 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -226,7 +226,7 @@
     // Enables an overlay to be displayed with the current refresh rate
     void enableRefreshRateOverlay(bool enable, bool setByHwc, bool showSpinner, bool showRenderRate,
                                   bool showInMiddle) REQUIRES(kMainThreadContext);
-    void updateRefreshRateOverlayRate(Fps vsyncRate, Fps renderFps, bool setByHwc = false);
+    void updateRefreshRateOverlayRate(Fps refreshRate, Fps renderFps, bool setByHwc = false);
     bool isRefreshRateOverlayEnabled() const { return mRefreshRateOverlay != nullptr; }
     bool onKernelTimerChanged(std::optional<DisplayModeId>, bool timerExpired);