Wake up disp sync thread when setting display period

Bug: 10624956
Change-Id: I272c15f319521bfbd1bb70451366c7dd84d60bf9
diff --git a/services/surfaceflinger/DispSync.cpp b/services/surfaceflinger/DispSync.cpp
index 7e67138..b2a604c 100644
--- a/services/surfaceflinger/DispSync.cpp
+++ b/services/surfaceflinger/DispSync.cpp
@@ -397,6 +397,7 @@
     Mutex::Autolock lock(mMutex);
     mPeriod = period;
     mPhase = 0;
+    mThread->updateModel(mPeriod, mPhase);
 }
 
 void DispSync::updateModelLocked() {