puzzles: change default optimization to -O2

Change-Id: I606df468f92f8d550827c122a9cfd5248866afdb
diff --git a/apps/plugins/puzzles/puzzles.make b/apps/plugins/puzzles/puzzles.make
index 520fd46..ad2a8a0 100644
--- a/apps/plugins/puzzles/puzzles.make
+++ b/apps/plugins/puzzles/puzzles.make
@@ -42,7 +42,7 @@
 ROCKS += $(PUZZLES_ROCKS)
 endif
 
-PUZZLESOPTIMIZE := -O3
+PUZZLESOPTIMIZE := -O2
 ifeq ($(MODELNAME), sansac200v2)
 PUZZLESOPTIMIZE := -Os
 endif