surfaceflinger: fix sorting in LayerProtoParser

"return (lz > rz) ? 1 : -1;" is equivalent to "return true;" here.

Test: dumpsys
Change-Id: I13b2784c500684eaf68a8a9706e3e864d43d95f2
diff --git a/services/surfaceflinger/layerproto/LayerProtoParser.cpp b/services/surfaceflinger/layerproto/LayerProtoParser.cpp
index a5bf9c1..bf12df6 100644
--- a/services/surfaceflinger/layerproto/LayerProtoParser.cpp
+++ b/services/surfaceflinger/layerproto/LayerProtoParser.cpp
@@ -31,7 +31,7 @@
     int32_t lz = lhs->z;
     int32_t rz = rhs->z;
     if (lz != rz) {
-        return (lz > rz) ? 1 : -1;
+        return lz < rz;
     }
 
     return lhs->id < rhs->id;