Remove extra sync wait in PostWorker

... as ColorBuffer::postLayer() and ColorBuffer::postWithOverlay()
already perform the waitSync().

Bug: b/233939967
Test: presubmit
Change-Id: I819829cde3b34b7658e70c2604bebed49990063a
diff --git a/stream-servers/PostWorker.cpp b/stream-servers/PostWorker.cpp
index bb11dd0..ce99fb5 100644
--- a/stream-servers/PostWorker.cpp
+++ b/stream-servers/PostWorker.cpp
@@ -127,8 +127,6 @@
     int zRot = mFb->getZrot();
     hwc_transform_t rotation = (hwc_transform_t)0;
 
-    cb->waitSync();
-
     // Find the x and y values at the origin when "fully scrolled."
     // Multiply by 2 because the texture goes from -1 to 1, not 0 to 1.
     // Multiply the windowing coordinates by DPR because they ignore