Revert "r306473 - re-commit r306336: Enable vectorizer-maximize-bandwidth by default."

This still breaks PPC tests we have. I'll forward reproduction
instructions to dehao.

llvm-svn: 306792

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -122,7 +122,7 @@ static cl::opt<unsigned> TinyTripCountVectorThreshold(
              "value."));
 
 static cl::opt<bool> MaximizeBandwidth(
-    "vectorizer-maximize-bandwidth", cl::init(true), cl::Hidden,
+    "vectorizer-maximize-bandwidth", cl::init(false), cl::Hidden,
     cl::desc("Maximize bandwidth when selecting vectorization factor which "
              "will be determined by the smallest type in loop."));