[Backend] Vectorize Load/Store Ops (#86)

This PR does the following things:

- Code refactoring on Load and Store op codegen, rewrite with same logic
and share much code
- Support the vectorized load/store

lib/Analysis/AxisInfo.cpp

@@ -214,4 +214,4 @@ ChangeResult AxisInfoAnalysis::visitOperation(
   return result;
 }
 
-} // namespace mlir
+} // namespace mlir