Update SurfaceFlinger FIFO configuration.

- move SurfaceFlinger main thread to prio 2
- drop EventThread from FIFO but not SFEventThread, which is still FIFO
prio 1
- make DispSyncThread FIFO, prio 1

bug 30481949

Change-Id: Ifedccfbf3cf144ffad030109849a924dddae8d09
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 5a0f706..a36a8cd 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -465,18 +465,13 @@
         mSFEventThread = new EventThread(sfVsyncSrc, *this);
         mEventQueue.setEventThread(mSFEventThread);
 
-        // set EventThread and SFEventThread to SCHED_FIFO for minimum jitter
+        // set SFEventThread to SCHED_FIFO to minimize jitter
         struct sched_param param = {0};
         param.sched_priority = 1;
-        if (sched_setscheduler(mEventThread->getTid(), SCHED_FIFO, &param) != 0) {
-            ALOGE("Couldn't set SCHED_FIFO for EventThread");
-        }
-
         if (sched_setscheduler(mSFEventThread->getTid(), SCHED_FIFO, &param) != 0) {
             ALOGE("Couldn't set SCHED_FIFO for SFEventThread");
         }
 
-
         // Get a RenderEngine for the given display / config (can't fail)
         mRenderEngine = RenderEngine::create(mEGLDisplay,
                 HAL_PIXEL_FORMAT_RGBA_8888);