SF: correct 90hz debug flags

debug.sf.set_idle_timer_ms > 0, debug.sf.use_90Hz == 0, was activating
boost to 90Hz. This corrects it so that if debug.sf.use_90Hz == 0,
then set_idle_timer has no effect.

Fixes: 124780321
Test: Manual systrace inspection
Change-Id: If926c086b5bdcf3645baa958bd19c7b163718728
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 3b4e456..2cb5baa 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -715,15 +715,16 @@
         ALOGE("Run StartPropertySetThread failed!");
     }
 
-    mScheduler->setExpiredIdleTimerCallback([this] {
-        Mutex::Autolock lock(mStateLock);
-        setRefreshRateTo(RefreshRateType::DEFAULT);
-    });
-    mScheduler->setResetIdleTimerCallback([this] {
-        Mutex::Autolock lock(mStateLock);
-        setRefreshRateTo(RefreshRateType::PERFORMANCE);
-    });
-
+    if (mUse90Hz) {
+        mScheduler->setExpiredIdleTimerCallback([this] {
+            Mutex::Autolock lock(mStateLock);
+            setRefreshRateTo(RefreshRateType::DEFAULT);
+        });
+        mScheduler->setResetIdleTimerCallback([this] {
+            Mutex::Autolock lock(mStateLock);
+            setRefreshRateTo(RefreshRateType::PERFORMANCE);
+        });
+    }
     mRefreshRateStats = std::make_unique<scheduler::RefreshRateStats>(getHwComposer().getConfigs(
                                                                               *display->getId()),
                                                                       mTimeStats);