SurfaceFlinger: remove mUse90Hz flag

As we have now DisplayManager changes in place (b/122905403)
there is no need for mUse90Hz flag. 90Hz will be enabled by
DisplayManager.

Fixes: 126725468
Test: Enable peak refresh from settings
Change-Id: I949727f8ba41bba874ab07160f3f6153d3bf4c67
diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index 7cd9e49..da34083 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -392,7 +392,7 @@
 void BufferQueueLayer::onFrameAvailable(const BufferItem& item) {
     // Add this buffer from our internal queue tracker
     { // Autolock scope
-        if (mFlinger->mUse90Hz && mFlinger->mUseSmart90ForVideo) {
+        if (mFlinger->mUseSmart90ForVideo) {
             // Report the requested present time to the Scheduler, if the feature is turned on.
             mFlinger->mScheduler->addFramePresentTimeForLayer(item.mTimestamp,
                                                               item.mIsAutoTimestamp, mName.c_str());